So, I usually use Paint Tool SAI when I want to add watermarks on the format of a skin. The steps on how I do it are:
Download the skin that you want to add the watermark on.
Open SAI and then select the Open option in the File menu.
Double-click on the skin and you'll see the skin's format
I use the Binary Tool 'cause when I use other tools it becomes blurry, For example:
It can also have Pixel as it's name. The size should be the smallest.
Add your watermark on the side or the top, for example:
But, It should be one pixel away from every pixel of the skin. It should go through the skin or more than one pixel away. Otherwise, it would show on the skin, For example:
something like that. I think that would be it! I DO NOT own this skin.
Alright I'll try that. Thank you!