The certificate of proof or acknowledgment may be given under seal or otherwise, according to the mode by which the officer making the same usually authenticates the officer’s formal acts. [C51, §1223; R60, §2231; C73, §1961; C97, §2951; C24, 27, 31, 35, 39, § 10098; C46, 50, 54, 58, 62, 66, 71, 73, 75, 77, 79, 81, §558.34 ]