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