SIGNAL FREE cannot be added to Kontakt the same way the full version of SIGNAL can. Below are screenshots from the on how to load SIGNAL FREE into Kontakt. Link to manual.
You can download Signal Free from here.
Choose the location you want to install it to and then you need to use Kontakt to load the free library. Once Kontakt is open, go to the floppy disk icon and select load then select Signal Demo > Instruments > Signal DEMO.nki file so it loads in Kontakt
