I want to make sure I have this straight.
Looking at the link you provided.
I aim at the bottom of the triangle type thing from 25yds and the bullet impact is in the center of the small circle for a 100yd zero, the top of the small circle for a 50yd zero and the bottom of the triangle type thing for a 25yd zero.
I would then go out to whatever distance zero i chose(in my case 50yd) and i should confirm my zero.
Im pretty sure im right.
Thanks.