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