The thrust/power relationship for the tail rotor is like any medium loaded disk. I am intimately familiar with the S76:
At a zero knot hover, it uses about 35 to 50 HP in a steady hover (51 HP at 11700 lbs comes to mind.)
At 50 knots sideward flight to the right, it uses about 400 HP.
The typical power consumption for a tail rotor is between 3 and 6% of the main rotor in a steady hover, and the peak TR power depends on the max sideward speed. At 17 knots, it is typically about 3 times the steady hover (making it 10 to 15%). But at those speeds, the MR consumes about 25% less power, so the net hover capability of the machine is somewhat better at 17 knots than it is at zero, even with the wind from the worst quadrant.