In the rich text editor:
@Hekkoki
In a comment:
[Hekkoki](https://chowlings.com/user/Hekkoki)
For Names and Avatars:
In the rich text editor:
%Hekkoki
In a comment:
[](https://chowlings.com/user/Hekkoki) [Hekkoki](https://chowlings.com/user/Hekkoki)