Okla. Stat. tit. 62, § 585

A. A certificated registered public obligation shall be executed by the issuer by the manual or facsimile signature or signatures of authorized officers. Any signature of an authorized officer may be attested by the manual or facsimile signature of another authorized officer. B. In addition to the signatures referred to in subsection A of this section any certificated registered public obligation or any writing relating to an uncertificated registered public obligation may include a certificate or certificates signed by the manual or facsimile signature of an authenticating agent, registrar, transfer agent or the like. C. At least one signature of an authorized officer, authenticating official or other person required or permitted to be placed on a certificated registered public obligation shall be a manual signature.