You should be able to set up a record in Sonar.
Create a new audio track and select the audio input that the Reaktor output goes to.
You may need to have a decent amount of RAM, but you should be able to run Sonar and Reactor simultaneously and record Skanner's output directly into Sonar.
I am not sure if NI will monopolize an audio interface or not, but Sonar 8.5 doesn't.