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