You can also adjust it without changing tinypic. In the coding for the siggy, do this:
Add in a space after the quotation for your photo link, then put: width="200"
Like this without the * and the correct file name:
<*img src="yourphoto.jpg" width="200">
The height will auto-adjust. I'm not sure if 200 is correct - it might be 250 or 300, but you can play with that to see what size looks right.