Aligning cart on Rega style arms without defeatable anti-skating?

Of course the first thing I did was to level the turntable, then zero out the counterweight and anti-skate to attempt to balance the tonearm.  When doing this it is obvious to see that the anti-skate was still somewhat active since the arm will slowly swing back to its rest. 

Just wondering if other Rega owners are experiencing the same thing, and whether this force is enough to deflect suspension any meaningful amount when trying to align to a protractor.

I am considering getting such a protractor but the issue isn't so much as to get the cartridge to land on the right spot of the protractor, but whether the anti-skate force pulling on the cantilever would cause it to sit askew and not "square" to the body once it is on the grid alignment point.