Signed documents such as POAs, prenuptial agreements, affidavits etc. – require a notary’s certification.
The certification includes recognition of the signatory, confirmation that the signatory fully understands the meaning of his legal actions and, in case an individual sign in the name of a corporation, confirmation of his authorization to sign.
According to the Hague Convention, all certificates of signature to be used in another country must be authenticated by an apostille confirmation.