Hello there,
I have been using this for some time now. I have a wooden pendulum. I use it just as described for healing purpose.
I test the polarity in the left hand with the pendulum. I always had a rotation, whether it is clockwise or counterclockwise. In the end it’s not that important. The rotation only indicates whether the energy is going outward or inward. I also say things when I do it like "What is the polarity of “insert_friend’s_name_here ?”.
Then I lay the person on her front and I work on her back (which is less intrusive for obvious reasons).
For testing I take the pendulum in the right hand, left hand is palm up wide opened on my leg, put it over the chakra’s location and ask : “that_chakra how is it ?”
The pendulum answers : rotation is good flow of energy. Movement in line, if weak is partial blocage, if strong is overstimulation, if no movement at all is big or total blocage, rarer but it happens.
The movement in line also has different ways : if the line is horizontal, the blocage, or the overstimulation is of the corresponding level.
Horizontality is the plane of materiality. For example, you have a house in California and you fear for it as the fires are closing in, that you are going to loose it all, it is the horizontal level.
The movement in line can also be vertical, then the matter is of more spiritual, or esoteric concern, for example you had a fight with someone, both said mean things, emotions expressed in a heated manner, guilt is being felt, there’s self inquiries following up, it is of the verticality, it is related to the self, to development, the spirit, the soul, ideals, etc.
So back to the testing, once I checked all chakras, I do the healing described by Ra and I check again.
For the healing, I was lucky to be told how to use a crystal (it’s a matter I have no knowledge of) so sometime I use a crystal, it is a small unmounted sphere of rock crystal. I just put it on the person’s back, my hand palm over it. It does act as an amplifier. Sometime it starts heating while my hands keep cold and the person’s back is not particularly hot. Just to let know that either you are the crystal, or you use a crystal as an amplifier. The clearer we become the less we need a crystal as the latter will compliment our own lack of quality.
All and any tool need to be cleaned including us as a tool. I clean the pendulum and the crystal with water. I also clean myself of course with several different practices that you can find in yoga, such as pranayamas and the like.
Hope it helps 
