Salty Splash, you need to resize your signature file in a photo editor (Microsofts Picture Manager or PaintShop Pro would do it I think).
The Forum FAQ suggests
'120 high, 400 wide. Max file size is 100KB'.
I suppose that is pixels.
It would need to be saved in .jpg format before you resized I think, if it isn't already.
Just had a look at your riverboat Lady Elgar whoo! luvly! Good blog