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