Rf4-usa-decrtd-ziperto.part1.rar -

This is the first segment of a multi-part archive. You will need all subsequent parts (part2, part3, etc.) to successfully extract the game. Extraction Guide

This likely stands for "Decrypted," meaning the file is ready for use in emulators like Citra without needing further conversion. RF4-USA-DecrTD-Ziperto.part1.rar

: Ensure you have every "part.rar" file in the same folder on your computer. This is the first segment of a multi-part archive