California Code, Business and Professions Code - BPC § 19215.5

Proof of compliance with Section 19215.4shall be made in the event of service by mail by affidavit of the director or his or her authorized employee showing this service by mailing, together with the return receipt of the United States post office bearing the signature of the licensee or his or her agent.The affidavit and receipt shall be appended to the original accusation on file with the bureau. In the event of personal service outside this state, compliance may be proved by the return of any duly constituted public officer qualified to serve process in civil actions in the state or jurisdiction where the licensee is found, showing such service to have been made.This return shall be appended to the original accusation on file with the bureau.