Without researching the tax issues of RSRs specifically, the answer is always, yes, you must report all your taxable income on your tax return.
Any withholding is only an estimate. It might be too high or too low. The tax you actually owe is calculated on your tax return and takes into account all factors (income, dependents, other credits and deductions, etc.). You get one tax bill for the whole year, and you get credit for all your withholding and payments. If you were over-withheld, you get a refund, and if you are under-withheld, you owe an additional payment.
