If you haven't already done so, try to ctc the mfgr, and/or the installer, and/or any local lumber yards, and/or roofing/siding shops. Perhaps they have scraps. Other than that, it's the ususal practice that the homeowner be left a few sheets by the installer for such problems as yours. I have about 10 full sheets but I did my siding job.
Other than this, get as close a color as possible, place it behind the hole, and silicone it to the inside of the damaged sheet. THen, use clear 100% silicone to seal the entire 'edge' so water doesn't get in the hole. My best to ya and hope this helps.