No signed receipt is necessary. Actually, the more things you require to be signed for, the more potential violations you have, especially as the bank is monitored against the regulation and its' policies.
It mentions NOTHING in the reg about a signature. If it is the banks procedure to routinely provide, a simple letter to the customer "attached, please find. . . ' will suffice.
The reg and commentary are here.
http://www.bankersonline.com/regs/12-1002/12-1002-014.html