I've pushed every button, read every PDF, searched this forum, but cannot get Reaktor to work in Sonar X1. I did have it working at some point, because I wrote a song using it. Now in a new project, same settings and nada nada nada.
Certainly not very intuitive to use in X1 as a syth plug, if it causes grey hairs to make sound come out.
Both 32-bit and 64-bit Reaktor work fine for me in Sonar X1. You load it just as any other VST. There are 3 or 4 ways to load a VST, the easiest is to drag and drop from the Sonar VST browser on to an empty track.
Make sure you've set up the VST paths, scanned them, etc. The same process you'd use for any VST.