Because these two formats serve completely different purposes, you cannot simply change the file extension from .rar to .pkg . Doing so will corrupt the file. To successfully convert the contents, you must first extract the archive and then repackage it into a valid installer. Understanding the Core Concepts
Apple provides a native command-line utility called pkgbuild specifically designed to generate component packages. Open the application. Run the following command structure to build your PKG: rar to pkg
RAR to PKG: A Comprehensive Guide to Converting File Formats rar to pkg