Any candidate to be voted for at a recall election, other than the incumbent sought to be removed, may be nominated by petition, which petition shall conform to the provisions of the Charter, so far as applicable, relating to nominating petitions at primary nominating elections. Nominating petitions may be circulated upon the City Clerk’s certificate of sufficiency of the recall petition. Each nominating petition must be filed with the City Clerk within the time established in the ordinance calling the special election. The City Clerk shall ascertain whether or not the petition is signed by the requisite number of registered voters of the City, Council district, or Board district, as the case may be, in accordance with the requirements of the Charter and the City Election Code. The City Election Code shall govern the circumstances under which and process by which insufficient petitions may be supplemented.