S.C. Code Regs. § § 81-23
Service of any notice provided for in these Regulations upon any non-resident respondent who has been admitted to the practice of medicine or osteopathy, or upon any resident respondent who, having been so admitted, subsequently becomes a non-resident or cannot be found at his usual abode or place of business in this State, may be made by leaving with the Administrator a true and attested copy of such notice and any accompanying documents and by sending to the respondent, by registered mail, a like true copy, with an endorsement thereon of the service upon the said Administrator , addressed to such respondent at his last known address. The postmaster's receipt for the payment of such registered postage shall be attached to and made a part of the return of service of such notice. The panel or Board before which there is pending any proceeding in which notice has been given as provided in this section may order such continuance as may be necessary to afford the respondent reasonable opportunity to appear and defend. The Administrator shall keep a record of the day and hour of the service upon him of such notice and any accompanying documents.
S.C. Code Regs. § 81-23