Dependiing on what you have downloaded, the file might not even be an original ‘rar’ file. If you open the file (can use winrar on your pc for this) and it contains images and stuff for the theme, instead of extracting the files, just rename the original XXXX.rar to XXXX.utz. You can then send this XXXX.utz file direct to the phone.
If the extracted file in the original rar file contains a utz file, extract it and send that to the phone.
A lot of people rename the files from utz to something else, namely zip/rar files, as some servers require a std file type in order for it to accepted as a downloadable file.