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