S.D. Codified Laws § 18-4-3

Indian agents or superintendents are authorized to take acknowledgments or proofs of deeds or other instruments in writing, in Indian country, and acknowledgments or proofs so taken shall have the same force and effect as if taken before a notary public. To qualify for taking such acknowledgments or proofs, such Indian agent or superintendent shall file for record in the office of the register of deeds of the county in which he is stationed, or the county to which said county is attached for judicial purposes, a certificate signed by the secretary of the interior of the United States showing his appointment and authority as such Indian agent or superintendent.