All aspect ratio is in the specific .cfg files. Location where you copy
it, is in a textfile. All you have to do is to rename the .cfg to your
right game name (SLUS-0123 to SLES-0123 if you use PAL Games) (Or your
Full Game name if you dont Use the Codes).
-Some of my Best of Games with correct .cfg for Retroarch:
Google Drive Download
-Added a complete png pack from PSX Bezels project to Google Drive.