An officer of the Foreign Service may administer an oath to a person making an affidavit to the effect that legal process has ben served. When an affidavit stating that legal process has been served is executed before a foreign notary or other official, an officer of the Foreign Service may authenticate the official character of the person administering the oath. The fee for administering an oath to a person making an affidavit or for an authentication, as the case may be, is as prescribed under the caption “Notarial Services and Authentications” in the Tariff of Fees, Foreign Service of the United States of America (§22.1 of this chapter), unless the case is of such nature as to fall under the caption, “Exemption for Federal Agencies and Corporations” of the same Tariff.