Patent (provided its genuine & Not synthetic) can be stretched as it has an elasticity to the surface.
However there is a bit of a feel to it! this is one which I would defiantly recommend to your local repairer.
you can buy a spay leather stretcher which you spray inside the shoe, this retails (UK prices) at about the 3-4 pound mark. this is fine on "most" shoes but as mentioned before for patent it require a certain feel for how much.
A repairer will put them on a machine (
http://www.brilee.co.uk/hhplace/003.JPG ) which is far superior for 2-3 pounds. with the machine you can stretch lenght, width & even attach attachments for bunions & such like!
Lee