Some folks like to use elaborate devices to use to create a tone with their tuning forks. I've seen some shaped like a triangle which sit on a table, I've seen another which comes with a leg strap and holster so you can strap it to your leg like a six shooter. Occasionally, I use a tuning fork activator (aka hockey puck).
If you tap a tuning fork against a puck too hard, it creates what is known as a clang tone. You've heard it, sounds like a bang and the first time you do it, you wonder if you broke the fork. The clang tone will create a frequency or note different than the one printed on the tuning fork. A friend noticed this last week when the Solfeggio fork he was using should have been an F but was reading as an F#. He was tapping the fork too hard creating that clang tone. The clang tone will eventually fade and the correct note and frequency comes out. There is no permanent damage to a tuning fork when a clang tone is created.
If you are going to use a puck, tap lightly. You don't need a loud tone, just a good clear one. Better yet, if you are wearing jeans or have pockets, place the puck in your pocket then tap.
What Was That?
Imagine you are in a deep sleep and suddenly jolted awake by the sound of the telephone. That is what could happen each time you use an activator. When you/your client is easing into a deep state of relaxation, the sound of aluminum banging against hard rubber is not going to help their cause, or yours.
Respect the silence.
For weighted tuning forks, use the palm of your hand as I explain in this video: