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