It's not rocks you are looking for -- it's trees. Other than the place where you place the short staff, of course.It's really hard to see them unless you are almost nose-to-bark against the tree -- it helps to temporarily set your monitor to the highest contrast and brightness so you can see them. Once they've been pressed, they show up better on normal brightness/contrast. What I did was to print out a copy of the map so I could be sure which trees I needed to touch. It doesn't matter what order you touch them in, though -- it's just easiest to start with the one farthest away and work your way in.
Just make sure you have the short staff with you before you touch the 6th rune because if you leave the area once you've triggered all six, they won't work when you return. You can trigger some of them and then go off and come back, but not all six.