The RarTools are owned by RARLAB. For more information about these tools, please visit their website. This tools must be installed.
There are two ways to install RarTools. The first is the most simple, when you open RarMachine for the first time it will ask you to install RarTools automatically.
In some cases it may happen that the installation can't be done. Try repairing your permissions and try again. If the problem still exists, you must do so manually: