Steve is correct. The fuel verification ONLY gives a rough check of the fuel quantity system and gives the beancounters an indication that they're not getting cheated by the refuelers.
The FQ system already accounts for fuel density, so with an operational FQ system the fuel mass is already calculated. No corrections to performance need be made.
The exception (and I've NEVER seen it) is when the SG is outside the normal limits for the aircraft. In that case an adjustment to max ZFW and/or TOGW may have to be made.