you can have you sig at 600 x 300 max but if you want to also use your pitapata , im pretty sure you will have to make your sig smaller to fit both into the 600 x 300 set space for your sig , when you resize it are you replacing the existing picture or saving new ? as i have found sometimes with photobucket if you save over existing the resize doesn't work some times .
I first saved over original picture. Then when I went to preview it, it was very big. I went back into Photobucket and resized it again and saved it as a copy. It is still very large. Finally I went back to Photobbucket and when I resized it, I saved it as medium (300x200) I think. Still very big.