I can't use Referrer Name in a form field or calculation

I can't use Referrer Name in a form field or calculation

Thanks to Manish's help, I have now got the Referrer Name field to record the URL of the page that called up a form, e.g. https://domain/gated-content/?source=lbbo-department.

Although I can see the Referrer Name field in a report or the Entries screen, I need to access it in one of the form's fields e.g. I would like to create a calculated field that says "if [Referrer Name] contains "lbbo-department", make this field "Little Black Book on Organising Your Department".

How do I refer to the Referrer Name field though? It isn't listed as one of the fields that's available for calculations.

I'd prefer to just put the Referrer Name into a hidden field but I can't seem to do that either.

Any ideas would be appreciated!

Many thanks

Steve