Load entries for drop down field from external source

Load entries for drop down field from external source

Hi, I'm loocking for a possibility to load a catalog of entries from an external source into a drop down field of a ticket form. Does anybody know a way how I could realise that?
I tried it with java script an the addOption in the field & form rules but I'm not able to add new entries I haven't defined for this drop down field before.

Thanks for your ideas!

Best regards,
Michael

                  New to ADSelfService Plus?