The recipient of a 5 percent loan from the Rural Electrification Administration or Rural Telephone Bank may subscribe for certificates under this offering, up to the amount of the unexpended portion of the loan, by submitting a subscription, together with the remittance, to the Federal Reserve Bank or Branch of the district in which the subscriber is located. The subscription form must show the amount of certificates desired, and give the title of the designated official of the subscriber authorized to redeem them.