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