/fʁoˈbeːniʊs/ (primary stress on the second syllable)
The r is more fricative, although a slightly rolling /ʀ/ is appropriate for more articulate pronunciation (e.g. when speaking in front of a larger audience without PA system). However, in some rural regions in the northwest, in the south of Germany as well as in Austria and Switzerland, natives will roll it stronger, like /ʀ/ or even /r/.
/ˈfɛʁdinant ˈgeːɔʁk fʁoˈbeːniʊs/
(In Ferdinand, the r is often slurred away completely, making it /ˈfɛːɐ̯dinant/. Some people will pronounce the first syllable more like /feːɐ̯/.)