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