Okla. Stat. tit. 28, § 28-102: Costs in civil proceeding to be proved by affidavit -

Taxation and collection.

All fees and sums paid by either party for fees of witnesses and

other necessary expenses, in any civil action or proceeding, shall

be proved by affidavit of the party or of some person knowing the

same to have been paid; and all such fees shall be taxed and

collected from the party ordered or adjudged to pay the costs.