I'm not 100% positive but I'm pretty sure that RAPID mode requires Samsung Magician to be installed in order for it to run.
If you uninstalled Samsung Magician (and then reinstalled it), what makes you think that RAPID mode is running? Are you getting some kind of message?
If the target drive drop down list is empty that means that Magician has not recognized your SSD, so I'm pretty sure that RAPID mode is not enabled.