Don’t know Illustrator, but in Inkscape you select the pad and just change the dimensions in the top tool bar.
Fritzing Part Creation - Chapter5 - PCB View
Drawing for PCB view, and checking outputs.
Note : The contact pad size used in this video is an example, use the applicable size for your application.
0:00 Overview
1:27 XML group format for PCB view
2:55 Correcting svg drawn with Adobe Illustrator
3:39 Unknown XML groups
3:51 SMD XML group format
4:20 Separate XML groups
4:22 Duplicated pads in both copper groups
4:49 Holes in PCB
5:31 Correct XML group format
5:52 Making an IC from sc…