Tutorial for Custom-Image-Flags:
Select your Favorite Image.
Go to http://www.ark-survival.net/en/image-to-board-sign-pnt-converter/
Put in your Image into the Converter.
Now Select "Canvas" in the Resolution 1x1 and klick on "Send"
(Optional) Now u can choose a custom Color at "Set Colors"
Press "Generate Preview" and download it.
Thats the important step! Copy your Image or Drag it into [Atlas Folder -> ShooterGame -> Saved -> MyPain