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