Any county or district board shall employ a director, who shall be the executive officer and secretary of the board, and shall be responsible to the board for the performance of his duties associated with those social service functions financed by the county. The director and his assistants shall hold no partisan elective office, shall devote their entire time to the performance of the duties of their office, and shall receive such compensation as shall be fixed by the state civil service commission, together with their actual and necessary traveling and other expenses incurred in the discharge of their official duties. Unless disapproved by the state civil service commission, the county board, with the approval of the county board of commissioners, may provide a supplementary salary to that fixed by the state civil service commission in remuneration for those duties of the director and his assistants if deemed justifiable, associated with the administration of those forms of relief or other welfare programs not wholly or in part financed by federal funds. The cost shall be deemed for all purposes a proper county expense.