The register
The register lists RSA Associates in Southall, MIddlesex as a licensed sponsor on Skilled Worker, an entry that goes back to at least 2026. Its rating on the register is Worker (A rating).
Companies House lists it as Rsa Associates Limited, number 08482500, incorporated 2013: 13 years of filings behind the name. The registered office is at 4 Badminton Villas, Bridge Street, Chepstow, NP16 5HB, NP16 5HB. Its filed activity puts it in professional and technical services. It has traded under other names before, including Rsar Associates Limited.
A licence says an organisation may sponsor; it does not say it is hiring today. The way to find out is the same as for any employer: the careers page, the job boards, and a direct approach with a UK-style CV that says early that sponsorship would be needed.