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