All claims against the city of Aberdeen for labor, services, supplies and/or materials shall be upon forms prescribed and furnished by the finance director, filed in the finance office, and shall be authenticated and certified by the department head of the department to which the labor, services, supplies and/or materials were furnished; provided, that the department head may designate the authority to authenticate and certify such claims to an employee within the department. A list of employees so designated shall be filed with the finance director.