Just seen this thread, if you haven't figured it out here's a quick video I shot while folding up the rear bench on my 96, should be exactly the same as yours.

YouTube - 96 F150 - folding up the rear bench seat

Basically grab the little loop and tug the rear of the seat bottom twards yourself, push the back on the seat cushion down so it lays flat on the floor. Then on the passenger side wedge your index finger between the seat and cab and lift the little latch up. Once the latch releases the rear of the seat will pop forward a little. Grab the back of the seat and push it down flat onto the floor.

If you have any large items under the rear seat you'll have to remove them so the seat can lay flat on the floor. As you can see from my messy cab papers and such just smush under the weight of the seat, but larger items will need to be removed.