This is the “classic” Rick Welch anchor:
The first anchor is a moving anchor. The thumb is cocked like you were cocking the hammer of a revolver, and it is left in the cocked position as the cocked thumb knuckle brushes the bottom of the earlobe. Movement stops when the back muscles have been fully engaged, and the clavicle has moved as far toward the spine as possible.
The image Rick would like the shooter to keep in mind is the back of the drawing elbow pressing as hard as possible against some immovable object, such as a pole or post in the ground, and maintaining this back pressure, which is really back tension, until the arrow is in the target. Rick practices this as part of the lessons with a real pole in the ground until it can be visualized with an imaginary pole, and advises that students keep up this practice at home from time to time with some real object so the image of pressing against an immovable object at full draw can be visualized every time the arrow is shot. This is a part of Rick's general advice of looking at the target at full draw while thinking about the shot. One of the “thinking about the shot” parts is visualizing the back of the elbow pressing against a pole. This really is one of Rick's anchors too, albeit an imaginary one.
After back tension is fully established and locked off, the shooter places his nose against the back of the cock feather. This anchor establishes a fixed, repeatable distance between the dominant eye and the top of the arrow. The student quickly learns where to place his nose in order to avoid having it hit by the bow string. After this, final aiming is done for about 2 seconds, and then, in Rick's words, “wait for the shot to go off.” Nothing is consciously done by the shooter to trigger the shot. In fact, having absolutely no movement when the shot goes off is key to the accuracy of his system.
Anchors depend on the structure of the shooter's face, and Rick will change his “classic” anchor to suit an individual student's physiognomy. We all tend to change our own anchors from time to time as we age or have new ideas about how to do things. He may even change his own anchor, i don't know. What he will never change is coming to full back tension and locking off before he drops his nose to the feather and completes his final aiming. I know, moving your head after coming to full draw is considered bad form by most, but Rick is not the only top shooter I have seen who does that.
Note that in Rick's system of instinctive aiming, the shooter does see the sight picture in his out of focus peripheral vision, while the target remains in focus. What makes his system instinctive as opposed to gap is that Rick allows his mind to come to a shot solution without conscious input from him. I'll admit, for a long time I thought his instinctive system was identical to Howard Hill's split vision, where the shooter does direct the arrow point to a chosen, uncalculated location. But finally, by observing some things that are outside the scope of this answer, I convinced myself that he really has no conscious input into the aiming process, so his system is truly instinctive, and not split vision.