How much to move it?

1) Find the sight radius by measuring the distance between the front and rear sight.
2) Divide this measurement into the range in inches you are sighting in at. this gives you a "Radius Multiple"

Whatever you move the rear sight will move the impact on the target by this multiple.

Example:
Sight radius= 5 inches
Yardage 25= 900 inches

900/5=180 (Radius Multiple)

Moving your rear sight 1/16 of an inch (.0625) will move the point of impact 11.25 inches at 25 yards

Working the other way divide the amount you want to move the point of impact on the target by your "Radius Multiple" and you will get the amount to move your rear site.

Hope this helps.