Rules on Civil Procedure
Section 19. Proof of service by publication. - If the service has been made by publication, service may be proved by the affidavit of the printer, his foreman or principal clerk, or of the editor, business or advertising manager, to which affidavit a copy of the publication shall be attached and by an affidavit showing the deposit of a copy of the summons and order for publication in the post office, postage prepaid, directed to the defendant by registered mail to his last known address. (21)