Install Playnite on your PC
Install RetroArch on your PC
Open RetroArch and download the cores you want to use
Note the full path to the RetroArch executable
Note the full path to the RetroArch cores folder
Open Playnite
Go to Library
Click Add-ons and install any needed emulator-related add-ons if desired
Go to Settings
Open Emulation
Click Add emulator
Set the emulator name to RetroArch
Set the emulator application path to the RetroArch executable
Set the emulator arguments to use the selected core and game file
Add the core path if needed in the arguments
Save the emulator
Go to Platforms
Assign RetroArch to the platforms you want to emulate
Go to your game library
Add your ROMs to Playnite
Edit each game’s emulator settings if needed
Set the correct core for each system
Set file associations for supported ROM extensions
Test-launch a game from Playnite
Adjust command-line arguments if the game does not start correctly
Enable fullscreen or windowed mode in RetroArch if needed
Save all changes
Launch games from Playnite using RetroArch