It is necessary to locate the areas in the physical and the subtle body before one start Reiki session. But this is for a beginner. Those who are frequently using their hands develop sensitivity and can find easy access to the areas which need treatment.
Here is a tip which may help in finding out the area. The healer should keep both the hands apart at a distance of about 20 inches, with the palms facing each other. After five minutes he has to bring them together slowly. He has to observe the changes taking place during the process. If this simple exercise is done daily for a few weeks, one's perceptive faculty will increase.
But this is not an end in itself. There are many things one will experience first before he will be able to interpret and evaluate them properly. Certain similar sensations are experienced \>y many people and are helpful to form a key for proper interpretation. One will have to examine if the key is useful. One will have to observe whether and in what way perceptions deviate from the key. After all, it is one's own perception that matters. Initially one will examine common perceptions and evaluate their significance.