No acknowledgment of any instrument in writing conveying real estate, or whereby any real estate may be affected, shall be taken, unless the persons offering to make such acknowledgment shall be personally known to at least one judge of the court, or to the officer taking the same, to be the person whose name is subscribed to such instrument as a party thereto, or shall be proved to be such by at least two credible witnesses.
§ 442.200, RSMo