Tuttle Box - Put your foil in any board
Prone surfboards in general need the box further back than a SUP. This is because the lighter the board, the less lift you need to make and/or keep it foiling.
Think of your back foot on a prone board where you would like to place it when standing up into surf position. Generally, your foot will be close to standing directly on top of the mast when on a prone board or slightly forward of that position.
On a SUP, you can stand slightly aft of the prone position, so many stand on the trailing edge of the mast on their SUPs.
Box placement further forward creates greater lift and earlier planing but you will be standing further towards the nose to balance it.
Box further back usually helps the boards turn ability.
Lightweight riders need less lift and heavy riders need more lift so consider the riders size when choosing box placement. Tuttle Box Holes Template
Download and print this template to help you drill the holes for attaching the foil to the Tuttle box in the correct place on the deck of your board. Make sure the scale is set at 100% before printing, then check measurements to see if the scale is correct after you print it. The holes are 105mm apart, measure that on your template to confirm sizing of template is correct.