In the rich text editor:
@RavingRaeven
In a comment:
[RavingRaeven](https://chowlings.com/user/RavingRaeven)
For Names and Avatars:
In the rich text editor:
%RavingRaeven
In a comment:
[![RavingRaeven's Avatar](https://chowlings.com/images/avatars/default.jpg)](https://chowlings.com/user/RavingRaeven) [RavingRaeven](https://chowlings.com/user/RavingRaeven)