It is unseen, and like the Marconi waves, it passes through intervening obstacles and seeks the person attuned to receive it.

In order to treat persons at a distance, you must form a mental image of them until you can feel yourself to be en rapport with them.

This is a psychic process dependent upon the mental imagery of the healer.

You can feel the sense of rapport when it is established, it manifesting in a sense of nearness.

That is about as plain as we can describe it.
It may be acquired by a little practice, and some will get it at the first trial.