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