Any authority constituted pursuant to the provisions of this article or Article 1.1 (§ 53.1-71.1 et seq.) may appoint as its fiscal agent the treasurer of a county or city which is a member of the authority, or in the case of member jurisdictions where there is no treasurer, the director of finance. No treasurer or director of finance shall be appointed as fiscal agent without their concurrence. In the event such treasurer or director of finance is appointed, all disbursements on behalf of the authority shall be by warrant signed by the chairman of the authority 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 authority and the treasurer or director of finance. Such salary supplement and expenses shall be borne exclusively by the authority and not by the Compensation Board.