beeker77, there is a formula but I don't know it. Search is your friend!
It is a real small amount though, not even close to a full screw turn, like tenths of an inch or hundreths.
Make a small witness mark, a tiny scratch, of your starting point on the sight base and the sight. Less is more.
Shoot a group then adjust(?) and repeat as necessary, until you're hitting where you want.
Before you start check the front of your sight base for a hole with screw in it that locks the sight. It is called a "Grub Screw" and takes a slotted tool that may or may not be found on the firing pin removal tool handle. They can be made by cutting a notch in a 6mm socket, I think. Check out Surplus Rifles.com or ask Tikirocker how to make the tool.
Good Shooting