As with the hose bracket and other tubular pipe
It is hard to mark the wall for an anchor. The pencil
Is too thick to fit into the hole. I guess you could get
A large thin punch or nail and mark it that way.
Or is there a very thin pencil to mark the wall.

The nail approach is easiest. You could also lay a sheet of paper over the tubing and do a rubbing over the holes, then transfere the papper to the wall.

Thank You