A coin is borrowed, signed and vanished. You now remove a boxed deck of cards. The cards are removed from the box with empty hands and you proceed to have one selected and signed. The signed card is cut in to the deck and the deck is tabled (there are no breaks in the deck) you instantly cut the deck and right there at the exact position of your cut is their signed coin sitting on the top of the remaining cards.
Your spectator removes the coin and turns over their signed card.