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