"Lenik himself suggests that "the handprint is that of a shaman who has marked the area as a sacred site. The boulder, standing alone on the hilltop, may have been seen as a source of spiritual power. The carving of the handprint may have been a shaman's attempt to derive power from the site."
Hand Rock: http://nemasket.blogspot.com/2009/05/hand-rock.html
Adding an edit, linking to a previous post because Chris Pittman said:
How this place looks today: http://rockpiles.blogspot.com/2010/07/indian-hill-middleboro-ma.html