You might perform a notarization on a document that is meant to be used outside of the United States. It is important to remember that these documents require authentication by the Secretary of State. The purpose of the authentication is to verify the signature(s) of the public official(s) on the document. Remember that you have been appointed as a notary public. So the Secretary of State is authenticating your authority to perform a notarization.
There are two types of authentications that can be performed on a document that is going to be used outside of the United States. These are apostilles and certifications. Which one to use is determined by the country where the document is to be used. Also remember that apostilles and certifications are performed only on documents meant for other countries. They are not issued for documents that are to be used within the United States.
You may be asked for proof of your appointment if you are notarizing a document that is going to be used in another country. The requirements of different states or countries differ, but this verification may be obtained from Secretary of State. It is the burden of the client, not the notary public, to determine the requirements of the state or country where the document will be used.