Resizing signature on Adobe Reader on Windows 7 tablet

Question

I have a Windows 7 tablet and would like to be able to complete PDF forms, and put a signature on them. However with Adobe Reader I am unable to resize the signature as I cant accurately touch and drag the signature to the smaller size I want. I cant "click" the outside corner of the signature to resize it.

I tried the alternative programs:

Foxit reader - fine but cant put signature in, has a pen tool but I can't change the pen colour or nib size.

PDF annotator - Nice pen tool, but cant fill in the PDF form checkboxes!