Take the gravelly Limberlost Trail from the parking lot and enter a Hemlock Forest that George Pollock (https://www.nps.gov/shen/learn/historyculture/skyland.htm) helped to protect a century ago.  Pass a horse path and White Oak Canyon Trail to intersect the Old Rag Fire Road at Mile 0.4.  Turn left onto the road where a signs says "Horse Path, Skyland, Big Meadows.  The FR drops down crossing White Oak Run.  Continue on and past two more bridle paths and aranger station at Mile 1.0.   Continue on down passing huge oak trees and the trail turns sharply left and comes to Corbin Mountain Trail at Mile 1.7.  Keep descending gently on Old Rag.  At Mile 2.2 pass Corbin Hollow Trail and begin to look for the Robertson Mountain Trail just ahead where you will turn LEFT.  Go another 0.25 miles and the path becomes climbing with several switchbacks.  At Mile 3.1,  the trail passes the summit on you rright so begin looking for a spur trail leading to various outcrops.  The White Oak canyon is below.  Hawksbill Mountain looms tall to the SW.

Meet at Limberlost Trail Parking Area at Mile Marker 43.0 Skyline Drive, Shenandoah NP