When dealing with unknown archives like this, it is important to follow standard security practices:
: Available on the App Store for Mac users. 763_1_RP.rar
If you trust the source and want to see what is inside, you can use common extraction tools: : The native application for this format. When dealing with unknown archives like this, it
: A free, open-source alternative that supports most .rar files. 763_1_RP.rar