Dig a shallow trench along both sides of the stone-edged path, using a shovel. Make the trenches deep enough for about half of the thickness of the edging stones and 2 inches of gravel.
Line each trench with landscape barrier fabric if you don’t want to have to deal with weeds growing between the rock edging.
Place 2 inches of gravel in the bottom of the trench. Use a hand tamper to press it into place.
Set the stones you selected along the edge of the gravel path. Push them firmly into the gravel base to seat them. As you work, try to keep the gravel path edging about the same height.
Fill in the remainder of the open trench with dirt, using a shovel.
Add more gravel to the path, as necessary. Keep the gravel below the top of the gravel path edging. Use a rake to smooth the gravel.