Referencing the above image starting from the left:
The body with the Sephiroth from The Tree of Life overlayed (minus the paths) represents 11 Power Points (Chakras) on the body. 4 of these Chakras are primary Chakras and, in general, any Reiki symbol can be used at the various Power Points.
In the center is the Tree of Life, including Da'ath and the 3 Veils. I have purposely left off all of the various correspondances so that this can be printed and filled in as needed (during a healing session perhaps, meditation, or pathworking). Additionally, I have drawn dashed horizontal lines in order to create soft borders where the 4 Qabalistic Worlds overlap... I have listed the 4 Qabalistic Worlds and the 4 Parts of The Soul to the right of The Tree of Life.
The Tree of Life is also overlayed on the Middle Pillar (Which I believe can be related to the Hara Line), and the Pillars of Severity (Feminine Energies) and Mercy (Masculine Energies).
To the right of the 4 Worlds/Soul Parts I have placed Reiki symbols in a specific Qabalistic World based on how I feel they resonate (For now I am only including the 4 shown). This is not indicating that only specific symbols can be used in specific places, it is descriptive of the symbol's resonate vibration (Low to High, relatively speaking). A guide to how the symbols can assist in "raising vibration", altering the state of consciousness, and focusing healing energies on physical/mental/emotional/spiritual problems (As well is directing energies and forming intents). The Sephiroth also correspond to states of consciousness, each one exposing you to various energies... Consider each Qabalistic World as being composed of its own Tree of Life resonating at that specific worlds resonate vibration(s), in other words each world is a Tree of Life itself.
In the same way that using particular combinations of symbols assists in targeting physical, mental, emotional, and/or spiritual problems. You can use particular combinations of symbols to access a Tree of Life for a specific Qabalistic World. For example, if I was working with a client on clearing a mental/emotional block I would work intuitively as I normally do and I would also use the Tree of Life resonating in Yetzirah as a guide/map, primarily using Sei Hei Ki and Hon Sha Ze Sho Nen to ultimately clear the blockage. This relates to a traditional Reiki application of Sei Hei Ki and Hon Sha Ze Sho Nen for Mental/Emotional Healing.
Practicing Qabalistic Reiki does require that you already be attuned to either Shoden (Level 1), Okuden (Level 2), or Shinpiden (Level 3) in a tradition/lineage of your choice. Study of the Hermetic Qabalah and pathwork are also required, pathworking using HSZSN and/or DKM works very well but you will need to be at least Reiki Okuden to use the symbols. As you progress through the paths of the Tree of Life Qabalistic Reiki becomes personalized to the practitioner.
More to follow as I walk the paths of the Tree of Life and share my experiences.