I had the very same prob. In my HRC manual it says that the top yoke should be drilled and then tapped just to the left and on the forward facing side of the pinch bolt. They then give a part number for a small bracket to hold the reservoir. (45517-NL5-700) this is a race kit part for an RC45.
I decided (after finding the price of a new yoke) not to drill it and made a bracket from a RC30 reservoir bracket and did mount on the top pinch bolt. It sits very well but as soon as i get an old yoke i will drill it and mount is as HRC say. I wouldnt worry too much about putting it on the pinch bolt tho its not the greatest place to mount them.
Heres a pic of mine... i hope andy doesnt mind a picture on here??
