You wouldn't see them reported on the various "taxes" boxes of your W-2 since they typically are not broken out separately in Box 14, even though the compensation created by the vesting of the RSU usually is. "Compensation" requires "withholding" and the only place to report the withholding is on your W-2.
If you are asking the question because when you entered the sale or sales of the stock your taxes went way up and you somehow think that now you need to report the withholding to bring that number down, that's almost certainly not the case. You only get to deduct the withholding once. The more likely culprit here is that you're using the wrong basis; you basis is not $0 as reported by the broker on the 1099-B. Your correct per share basis is the same per share "fair market value" used by the employer to calculate the compensation created by the vesting.
Tom Young
