Slateman - All the points above are valid and true. But let me address your question from a different angle.
Zero your rifle at 100 yards: That means, you've adjusted the turrets such that the bullet impact is in the same spot as the center of the cross hairs. Then you will loosen your turrets, and adjust them to "0" and tighten.
No matter what power you are on, that center is unchanged (unless you have a POS scope, which is another story). So, at 100 yards, you bullet should go right at the center of the cross hairs, no matter what power you are on.
Now we go back to 300 yard. It seems you are conflating 2 distinct elements of operating the scope. Dialing the turrets and hold-overs using the reticle. Let's take them one at a time:
Turrets: At 300 yards, you can dial the turret to your 300 yard dope (for me it's 1.1 mil). Then you should be able to hold center and the bullets will hit point of aim - regardless of the power setting.
Hold over: You can also leave your turret at "0" and hold 1.1 mils using the reticle. However, this will only work at the designated power setting for the SFP scope - for yours, that should be 14x. If you put it on a different power setting, a 1.1 mil hold will not be 1.1 mils. If you feel ambitious, you can calculate the values of different power setting and confirm via calibration etc.
This is why FFP scopes are so popular (but more expensive) the reticle subtends the same distance at any power setting. 1.1 mils will work at 300 yards at any power setting.