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