The "IF" is an internal footing. I'm using a short, 2" to 5", length of carbon tubing glued into the front of the arrow. The IF makes the front of the shaft extremely stiff and makes the arrow act stiffer, I shoot full length shafts so I'm effectively shortening the working spine of the shaft; the shorter the IF the closer the arrow spine is to what's marked, the longer the stiffer. I draw in the neighborhood of 32" so finding a shaft that's stiff enough to shoot heavy points is nearly impossible which is why I'm experimenting with the IF.
I could add weight to the nock end but I'm trying to get a somewhat high FOC so the weight on the back of the arrow would negate the heavy point.
With everyone's help I think I'm really close and I glued up four shafts today with 2" IF's and I'm hoping that does the trick. It appears for every 1" of IF added you can increase point weight by 40 to 50 grains.