In the rich text editor:
@Wifflebark
In a comment:
[Wifflebark](https://www.chowlings.com/user/Wifflebark)
For Names and Avatars:
In the rich text editor:
%Wifflebark
In a comment:
[](https://www.chowlings.com/user/Wifflebark) [Wifflebark](https://www.chowlings.com/user/Wifflebark)