Control over image sizes

Hello,
Can you recommend a way to control the image sizes coming in from FB? Mine are showing as really small thumbnails.

I see in the plugin folder->Recent Facebook Posts->classes->class-rfb-widget.php line 112 is how the data comes in from FB and is put into the widget li’s.

I see that Facebook allows us to use image sizing -> https://developers.facebook.com/docs/reference/api/using-pictures/

trying to figure it out now.
Any advice would be appreciated. Thanks for an awesome plugin!

http://wordpress.org/extend/plugins/recent-facebook-posts/