Resident+evil+4+ppsspp+iso+file+top+download+highly !!install!!

Do not just click the first link on Google. Avoid pop-up-heavy sites. For this specific search, look for community-vetted forums like:

Use the emulator’s save state feature to pause and resume your game anywhere, instantly. How to Install Resident Evil 4 on PPSSPP

Resident Evil 4 "PPSSPP ISO" files you find online are typically fan-made mods rather than official releases.