Okla. Stat. tit. 5A , app 7 R. 13
All subpoenas and other process shall be issued by the Court or the Clerk of the Court.
Any process may be issued to any county in the State of Oklahoma.
Process directed to be served in any county shall be sent to the Sheriff of the County in which the same is to be served, and shall be returned by him to the Clerk of this Court as now provided by law.
Service fees of the Sheriff shall be endorsed on the process and be paid by the Clerk of this Court.
In addition thereto, process may be issued by the Clerk of this Court and served in the manner provided in the Code of Civil Procedure of the State of Oklahoma.
In addition thereto, the Clerk of this Court is authorized to appoint a special process server to serve orders and process of the Court. Fees for service and expenses shall be as allowed by law.
Okla. Stat. tit. 5A , app 7 R. 13