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