It's the southern path you want if you're coming from Cutthroat Bridge. Follow it up from the bridge as it heads west along the route of the power lines until it gets close to the nature reserve (to the right of the Ford on the map I've posted). When I was there the land just before the reserve was very boggy and I had to find a way north round it through a lot of bracken before heading west again. There is a bit of a track that runs uphill (west) that will take you close to the drystone wall iirc and the Tor becomes fairly obvious as you walk up. You want to head for the highest rocks of the Tor and the carving is just below them on the southern side, my grid ref is SK20488689. On the way back I took a short cut through some old paddocks (where the rain gauge is marked) but then made the mistake of following the wall round the side of the reserve which leads you straight back to the bog and ended up having to climb the barbed wire fence into the reserve itself rather than risk the bog.
I've drawn a couple of routes on the map but an alternative might be to walk through the reserve then backtrack following the line of the wood north then east to get to the Tor - might be a stiff hike uphill though. Sorry I can't give you any more accurate directions but apart from the boggy area the rest should be fairly easy going.

-Chris