The subdivider, having received approval of the preliminary plat of the proposed subdivision, shall submit a final plat of the subdivision and drawings and specifications of the improvements required therein. The final plat shall have incorporated all changes in the preliminary plat required by the Planning Commission. Otherwise it shall conform to the preliminary plat, and it may constitute only that portion of the approved preliminary plat which the subdivider proposes to record and develop at the time. The final plat and the supplementary information shall be prepared by a registered engineer or surveyor.