These are the standard formats. If your game is in a folder (often containing an app folder), you should compress the contents of that folder into a .zip file for installation.
If you bought games on PSN:
(French American Game Decrypter) became the standard for taking the encrypted files from a real Vita and turning them into a format the emulator can read. The VPK Format : These decrypted files are often packaged as vita3k roms