474.337.  Written will self-proved, how. — 1.  A written will may at the time of its execution, or at any subsequent date, be made self-proved, by the acknowledgment thereof by the testator and the witnesses, each made before an officer authorized to administer oaths under the laws of this state, and evidenced by the officer's certificate, under official seal, attached or annexed to the will in form and content substantially as follows:

  2.  An officer authorized to administer oaths under the laws of this state, who has no official seal, including a commissioner of deeds acting under section 486.130, and a judge advocate or other commissioned officer of the Armed Forces acting under Article 136 of the Uniform Code of Military Justice (United States Code, Title 10, Section 936), whether or not on active duty, section 492.070, or an equivalent court rule, may, in lieu of affixing an official seal to his certificate, include in it a statement that he has no official seal and reciting the facts which establish his authority.  Such a statement has the same effect as an official seal.