The helicopter should be rotated through 10 - 20 degrees (and this should have been the wording in the RFM). The 20 degree rotation should be applied in low winds and reduced incrementally to 10 minimum in higher winds; if 20 degrees is used in higher winds, the helicopter will descend below the level indicated in the drop-down graphs.
The actual figure (between 10 and 20) is left to the pilot because it would be difficult to require an exact pitch attitude adjustment.
As you will appreciate it has to be this way because the attitude of the helicopter varies with CofG.
As indicated by Senior Pilot, it used to be the practice to level the 'wings' in the hover (or place it to some other level); this is no longer the practice - adjustable horizons are somewhat out of favour.
Jim