Thsi technique can also be used with the normal cross hair reticle. For example: If you use the post in the top of the field of view as your 100 yard zero, the cross hair would be (depending on your scope) 3.5 inches high at 100 yards, and the post at the bottom of the field of view would be 7" high at 100 yards.
inserting 3.5" high or 7" high @ 100 yards then using the ballistics program you would be able to determine at what yardage the bullet crosses the zero.
So, for a givin bullet weight, Ballistic Coefficient, Muzzle Velocity you would know that your rifle would zero at 100 yards using the upper post, zero at 250 yards (
just an example), and the bottom post would be say , 375 yards. I hope this helps.
Bob