Prior to purchasing a notary stamp, a notary must receive a certificate of authorization from the Secretary of State. The seal can “be...a circular design stamp or a rectangular design stamp...and be surrounded by a border”. A North Dakota notary who performs a notarial act involving a tangible record must affix an official seal to each notarial certificate at the time of notarization.
Source: NDCC 44-06.1-14[2] and 44.06.1-23[8]