I put the screenshot in Photoshop, crop it, and then check the image size.
What I'd consider your signature is this:
[Image: http://puu.sh/19WoR]
And the size is this:
[Image: http://puu.sh/19WpI]
If you don't have a way to check your exact size, this should be a good reference point:
[Image: http://i.minus.com/i4akc7gGSVUbz.png]