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