My first Reiki Master teacher, Diane McCumber, learned Reiki from Arthur Robertson and was taught both the Takata-style Usui system and the Raku Kei system. While I learned both from her in March 1989, she mainly taught the Raku Kei system. Later the same year, I was also taught the Usui system by Marlene Schilke, who had also learned from Arthur Robertson.
By combining the Usui and Raku Kei systems I developed the Usui/Tibetan system of Reiki. This system kept the four Usui symbols as taught by Takata Sensei and added the Tibetan symbols and violet breath as taught by Arthur Robertson for a total of six symbols. I taught this system from the beginning of my teaching practice in June 1989, when I taught my first class, and continued with this system through 2013.
Source: https://www.reiki.org/faqs/what-history-reiki