Go to this web site.
Devices like the Wally Skater can measure the amount of antiskating a tonearm's A/S device applies at any given point across the tonearm's arc of travel. However, any such static measurement taken when the stylus is not tracking a moving groove will not correspond to actual playback conditions.
Skating forces only exist during actual playback. They are constantly changing due to randomly occurring conditions within the record groove. No device that I'm aware of can measure actual skating forces, so any measurement of anti-skating is just data without useful content.
The most useful way to "measure" anti-skating is to assess its effect on stylus tracking and the musical signal. This is most easily done by listening.
I suggest starting with zero A/S. Nudge it upward in *tiny* increments until your rig tracks the toughest passages cleanly. As you increase A/S above that, HF's and dynamics (both micro- and macro-) typically become smothered and the music goes a bit dull. That's when you know you've got too much, so back off a little and you're as close as it's possible to get.
YMMV. The audible effects of skating and anti-skating depend on the rig, the listener and the individual LP. Yes, there are some who adjust A/S on an individual LP basis. But this is because they *hear* the difference, not because of any measurement.
In summary and IME, actually measuring anti-skating is a waste of time.