When you are wearing the LuckyCharm it will teleport you to the Lucky Chair and sit you on it as soon as it hears your letter.
After attaching the device, it will check whether you have RLV activated, and it will detect your letter. You will see some messages in local chat saying whether the configuration was successful. The messages are visible only to you.
If the LuckyCharm is attached to your HUD, you can touch it to turn it on and off.