Your taxable amount all depends on whether you received the RSU's as a 'gift' / 'bonus', or you 'paid' for the shares. Cost Basis is the key.
If the company issued the RSU as a bonus, and you paid nothing ($0) for the shares, then the cost to you was $0 regardless of the share price when the RSU was issued. In that case, even though the share price is lower today than when originally issued, since the cost was $0, you would have a taxable profit. (a lower profit than the original value, but still a profit)
If however you purchased these shares via WITHHOLDING (with funds from your paycheck) then your cost basis would be whatever the withholding amount was.