Here we go: Control the card you want to force to the top of the deck. Undercut about a quarter of the pack and throw it on top holding a break above the force card. Turn over the top card and give it to the spectator instructing him to partially insert it face up somewhere in the middle of the deck. Make sure it goes below the break. Take the deck in the Biddle Grip in your right hand transferring the break to your right thumb. Push the cards below the face-up card backwards with your left index finger while taking the deck in your right hand. Push the section above the break a bit forward with your right hand and grab the face up card and the section above the break at the short end of the deck between your right thumb and index finger and lift it up to show the face-up card at the bottom of this section. Now you have apparently cut the deck at the face-up card, when you've actually cut it at the break.