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