every dealer handles this issue differently.

some dealers will simply sign and give you a file copy off their ffl. you then order the receiver and mail off the ffl file copy with your order/payment. your ffl dealer receives the receiver and you simply pay him for the transfer ($20 in my area...sometimes $10 each if multiple x-fers).

other dealers will not relinquish their file copies and will mail them off only directly from their shop.business. he may still want you to order/pay for the receiver or he may do it all himself.

however it is set up, it is in your interest to assist the ffl holder inn every way to make sure the deal goes smoothly.