Here's something Stefan Grossman posted on his forum last August regarding right hand position.:

"It's all down to the sound you produce. It can be very helpful to rest your pinky and/or ring finger on the face of the guitar when playing fingerstyle blues. But it is not necessary if you can produce a strong sound without doing this. There are several examples I can cite:
1) Check out videos of great white/black traditional players, i.e. Rev. Gary Davis, Miss. John Hurt, Lightnin' Hopkins, Skip James, Son House, Mance Lipscomb, Merle Travis, Doc Watson etc. They all rested their pinky/ring finger on the face of the guitar. They're NOT pressing down but rather resting in this position which helps greatly to get your palm to sit on the bass strings to dampen the sound. Also most of them only used their thumb/index fingers to pick.

2) I played for years with John Renbourn. A great guitarist with his own sound BUT when he would play Cannonball Rag by Merle Travis (or other American fingerstyle instrumentals) he would change his right hand classical position to that described in #1.

3) There are NO rules. The criteria is the sound you make. During Workshops we usually start with having everyone play and we (me and the other students) listen and comment on the sound that is being produced. If we like it we don't recommend any changes - no matter what right hand position is being used. If we think the sound could be improved the first suggestion is usually to play with more commitment (which simply means to play stronger). Once we can hear the wood and strings of the guitar we then try to work on the nuances of the sound. When playing traditional fingerstyle the bass dampening can be very important and adds so much to your sound. At that point we check out the right hand position and see if this can be changed - presuming as listeners the sound isn't "turning us on".The acoustic guitar can have lots of sound and by resting your pinky/ring finger on the top can help dry out the sound so that you as the musician add richness, i.e. vibrato, dampening etc.

It is the sound you produce that is the most important element in music. Check out players you enjoy and watch their right hand positions and try to imitate. It's easy to play lots of notes but difficult to play music.
In my limited experience of 50 years of playing as well as recording/producing guitarists I would say that in 98% the resting of the pinky/ring finger is found in most players. It ain't no myth."

I don't advocate it, in fact I don't often do it but if I play a tune where I'm more comfortable dropping the pinky on to the face I do. My approach is similar to John Renbourn's as described in item #2 (Heavens, I hope no one is thinking I'm comparing my humble self to the late, great guitarist).