Hello Marc, thank you for posting this excellent question to Avanquest UK forum webpage.
RTL, VOX and NTV are included in this additional database file of channels for Online TV 13
Close Online TV software and click here to download the zipped database file. Decompress the file then double click on the file once downloaded and press OK after the import is complete.
Now start Online TV 13 and watch additional channels.
Avanquest Support team