No, you don't have to declare RSUs on your tax return as, you indicate, the tax is already paid.
You will have a CGT liability/gain depending on whether you made a gain/loss on the sale of your remaining shares. Your purchase price will be the Euro value of the shares at vesting date (this is what your PAYE was calculated on) and your sale price will be the Euro value of what you sold the shares for at date of sale.