Riverside Resources Announces Completion of Phase One Drilling at Union Project and Now Awaits Drill Assay Results

~Over 1600 metres drilled to date and 700+ samples shipped to laboratory~

Riverside Resources Inc. (TSXV: RRI,OTC:RVSDF) (OTCQB: RVSDF) (FSE: 5YY0) ("Riverside" or the "Company"), is pleased to announce the completion of the first phase of drilling at the Union Project in Sonora, Mexico. 12 diamond core holes were completed for a total of just over 1,600 metres across six priority targets. The work is being advanced with funding through partner Questcorp Mining Inc. ("Questcorp") under the option agreement announced earlier in 2025 with Riverside as Operator and managing the exploration program.

Program Highlights

• 12 core holes completed totaling >1,600 m.
• Six targets drilled: Union Mine, Union Norte, Cobre, Luis, Famosa, and Famosa Mag.
• Three past-producing mine areas tested adjacent to historic workings to evaluate continuity.
• >700 half-core samples shipped; assays pending.
• Holes oriented as angle and near-vertical to cut stratigraphy and structures typical of Carbonate Replacement Deposit-type ("CRD") systems, with focus beneath oxidized horizons generally <150 m depth.

"This first exploration phase accomplished initial drill holes into 6 target areas. We tested multiple shallow gold and base metals targets, confirmed the key carbonate host units recognized by historic mining at Union and Famosa, and gathered the structural and alteration data to further progress efficient mineral exploration," said Dr. John-Mark Staude, President and CEO of Riverside Resources. "This historically mined CRD district, validated by new drilling and improved datasets, advances our geologic model and supports the potential for a large-scale discovery. With six targets advanced and more than 700 samples at the lab, once results are received, we will scope the next exploration program and focus on the most prospective trends indicated by assay results, stratigraphy, structure, and geophysics."

Drilling Update by Area

Union Mine: Three holes at the Union Mine targeted manto horizons and chimney/feeder structures adjacent to historic underground workings. This reconnaissance drilling was designed to evaluate stratigraphy, alteration, and mineralization continuity typical of CRD systems.

Famosa Mine Area: Four core holes tested a west-dipping dolomite manto target and adjacent structures. Logging noted intrusive dikes and breccias; no geochronology has been completed. Historical small-scale mining left surface dumps reported with gold grades of >0.5 oz/t Au (>15 g/t) in an independent NI 43-101 report filed on SEDAR+, May 7, 2025, by Questcorp. An inclined shaft dipping ~70° to the west parallels the favorable horizon. Holes were drilled at angles toward the east to intersect the target as close to perpendicular as practical and to evaluate continuity of alteration and mineralization.

Union Norte: Two initial holes tested the manto horizon within dolomitic carbonate strata to evaluate continuity and geometry along favorable trends mapped near historic workings. This phase targeted the westward extension. Follow-up work, including possible step-outs to the east, will be considered after assays and geological interpretation.

Cobre and Luis: Each target was tested to assess style, structure, and controls on mineralization. Results to date show sulfides, mineralization types, and intrusions aligned with a carbonate-hosted metals system.

Figure 1: Map of drill targets and core drill hole locations for the 12 holes of Phase 1 program.

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Sampling and Assays

Core was logged, saw-cut, and half-core samples were shipped for analysis. Samples from the first eight holes were delivered to Bureau Veritas (Hermosillo, Sonora) for gold fire assay, with pulps forwarded to Vancouver, Canada for Inductively Coupled Plasma-Mass Spectrometry ("ICP-MS") following four-acid digestion to determine silver, base metals, and pathfinders. Samples from the final four holes were shipped to ACT Labs Zacatecas, where preparation, gold assay, and multi-element ICP are completed in Mexico. Remaining half-cores are retained for reference. The final 4 holes of the program were shipped to ACT Labs where they were similarly assayed using the same processing methods but with their initial preparation and assaying completed in Zacatecas, Mexico using the same ICP and gold fire assay methods.

Next Steps

After assays are received, the Company plans to announce results and begin work to integrate the full exploration results including the assays, core logging, geophysics, advance detailed multi-element geochemistry, and updated structural mapping to refine the CRD model and scope for a Phase 2 exploration campaign. The Phase 2 campaign will likely include more extensive drilling and other exploration work as this Phase 1 was only an initial sampling into some of the targets at Union. This next expanded drill program could take place in H1, 2026 as all permits and access are in good standing and with the new data targets will be ready to explore.

Qualified Person & QA/QC:

The scientific and technical data contained in this news release pertaining to the Project was reviewed and approved by Freeman Smith, P.Geo, a non-independent qualified person to Riverside Resources Inc., who is responsible for ensuring that the information provided in this news release is accurate and who acts as a "qualified person" under National Instrument 43-101 Standards of Disclosure for Mineral Projects.

About Riverside Resources Inc.:
Riverside is a well-funded exploration company driven by value generation and discovery. The Company has a solid balance sheet with no debt and less than 75M shares outstanding with a strong portfolio of gold-silver and copper assets and royalties in North America. Riverside has extensive experience and knowledge operating in Mexico and Canada and leverages its large database to generate a portfolio of prospective mineral properties. Riverside has properties available for option, with information available on the Company's website at www.rivres.com.

ON BEHALF OF Riverside Resources Inc.

"John-Mark Staude"

Dr. John-Mark Staude, President & CEO

For additional information contact:

Certain statements in this press release may be considered forward-looking information. These statements can be identified by the use of forward-looking terminology (e.g., "expect"," estimates", "intends", "anticipates", "believes", "plans"). Such information involves known and unknown risks -- including the risk that the Transaction will not be completed as contemplates, or at all, availability of funds, the results of financing and exploration activities, the interpretation of exploration results and other geological data, or unanticipated costs and expenses and other risks identified by Riverside in its public securities filings that may cause actual events to differ materially from current expectations. Readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this press release.

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