Should say

Most people have not yet heard about RPT psychology, but those who used this method left positive reviews.

First you should say about what RPT is. Literally «Rapid Personal Transformation» means therapy. It implies a comfortable method of getting rid of injuries, which are the reasons that cause certain problems in the life of each person. And it is precisely these injuries that are the main barrier of a person on the way to the achievement of happiness and true freedom.