In order for a document to be accepted by a Hungarian authority, you need to legalize your signature on it. For this you have the following options:
(Legalization of a signature means that the consul establishes the veracity of the signature only, and not the content of the document, for which the Consular Section bears no responsibility. The document will have to be drawn up by yourself in advance. We are unable to assist you in drawing up or typing out the document.)
1. Legalization of signature in a Hungarian representation in the USA
In order to legalize your signature, you need to come in person, present a valid identification document with photo (such as your passport, driver's license, residence permit) and sign the document in front of the consul. The fee for EACH signature to be legalized can be paid in cash or money order (personal checks cannot be accepted).
Hungary and the United States of America are member states of The Hague Convention of 5 October 1961 Abolishing the Requirement of Legalization for Foreign Public Documents (please see here for further information).
A document having an "Apostille" will be directly accepted in Hungary without needing any further authentication by a Hungarian representation. You can have your signature legalized by any public notary, then ask your local Secretary of State to attach to the document the "Apostille" authentication.