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