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