Thank you @cjoseph for the beta version you send me.
I just applied 6.4.4.4-4.2.3.0_53593 on the device. As a result I have more options for "AppRF visibility" (App, WebCC, All, None). Also the setting "URL visibility" appeard which wasn't present in the past.
Setting "AppRF visibility" to "All" resulted in the exected result: The "AppRF" is visible in the administration interface.