Conversion of rar files to obb file format

It doesn't look like that some simple way how to convert random .rar archive to Android .obb package exists. Nonetheless, if the content in the .rar file is really for one of your apps (.apk), it usually means that there is .obb file inside the RAR archive. You will need to extract the .rar file first and then place it in the default obb folder on your SD card.

Open RAR file    Open OBB file