Hi @mlauber71,
Thanks for reply and comments
yes unfortunately that is the case. I have compiled a list to follow if you want to get R up and running with KNIME even with MacOS. Maybe you have found it.
Can you give a link to “the list” please?
My experience: R compiled fine, Rserve 1.8-6 worked after solving a problem finding libssl.a. Needed to compile openssh, change paths etc. Gave up after Rserve refused to start, looking for libR.dylib. Frankly I am afraid of breaking my system since I am not massively experienced in OSX sys admin.
Agree that a fully functional KNIME and R integration would be very useful and appreciate it is possible given time and adequate knowledge of OSX standard setup, which package managers to use, how to supply correct paths to make, configure and R install.packages() 
All the best
Sean