Thank you PaKa. I appreciate the help. I am currently working on setting up and running that example using nRF Connect SDK. 

But I wanted to confirm the possibility of configuring DF mode using just the softdevice or the radio drivers. What if I want to use the nRF softdevice sdk with s140. Is it possible to configure the DF mode and enable CTE when using a softdevice? As I mentioned before, I just want AoA tx i.e. I want to send a advertising packet with CTE appened after the CRC. How would I approach that? Please let me know.