In the rich text editor:
@Speedy
In a comment:
[Speedy](https://chowlings.com/user/Speedy)
For Names and Avatars:
In the rich text editor:
%Speedy
In a comment:
[![Speedy's Avatar](https://chowlings.com/images/avatars/1660.png?v=1663201862)](https://chowlings.com/user/Speedy) [Speedy](https://chowlings.com/user/Speedy)