Pleadings, motions and other petitions shall contain a caption setting forth the name and address of the Commission on Audit, the title of the case, the docket number and the description of the pleading. They shall be printed or typewritten double-spaced on legal size bond paper. Proof of service of such papers on the adverse party or auditor, Director, or other parties having a direct interest in the case is necessary and must be shown therein.