Skating force is the product of the stylus' friction in the groove times the (imaginary) lever arm, whose length is the distance between two parallel lines: one, the L/R center-line of the cartridge and the other, a line parallel to that one but drawn through the main vertical axis of the tonearm's rotational main bearing. This lever arm distance remains the same no matter where on the record the stylus is; and unless the stylus' friction in the groove varies from outside to inside grooves, the skating force remains constant (although it's higher on loud passages due to more groove friction ;-)
If your tonearm has no headshell offset, nor an 'S' curved armtube, then no skating force will develop and you don't need any antiskating force. This is OK for 12" and longer tonearms which don't have much tracking error anyway.
The easiest way to check anti-skate (without an oscilloscope ;-) is to just look at the cantilever dead on as you lower the tonearm to the record. If just as the stylus goes into the groove, the cantilever shifts to the outside (relative to the cartridge body) you need more AS. If it shifts to the inside, you have too much. Note: (a.) This takes a little practice and a lot of light. (b.) It's easier to do with high compliance (MM) cartridges than with low compliance (MC) cartridges because squishier suspensions (MM) make the cantilever shifting easier to see. However after a little practice, it IS possible w/ MC cartridges. And anyway, this is to get you in the ballpark; final adjustments (no matter what method you use) will have to be made by ear. (Tip: try doing your listening tests with a mono record.)
Although the visual (+listening) method described above is as good as any I've tried, anti-skate adjustments render very subtle results. So it's exremely important that all other parameters be on the nose; including perfect azimuth, which is especially important when trying to find the correct AS force.
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