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