Any regional jail or jail farm constituted pursuant to the provisions of this article may appoint as its fiscal agent the treasurer of a county or city which is a member of the board of the jail or jail farm, or in a member jurisdiction where there is no treasurer, the director of finance. No treasurer or director of finance shall be appointed fiscal agent without their concurrence. In the event such treasurer or director of finance is appointed, all disbursements on behalf of the jail or jail farm shall be by warrant signed by the chairman of the board of the jail or jail farm or his designee and countersigned by such treasurer or director of finance as fiscal agent. For his services as fiscal agent, a treasurer or director of finance thus appointed may be paid such salary supplement and reimbursed such expenses as may be agreed upon by the board of the jail or jail farm and the treasurer or director of finance. Such salary supplement and expenses shall be borne exclusively by the regional jail or jail farm and not by the Compensation Board.