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