Where to find IPTC Extension

Dear folks,

I'm currently scanning my analogue negatives and came across the "Digital Source Type [IPTC Extension]". Is it possible to add this metadata field in Capture One Pro 9? So far I wasn't able to find it.

If not, where should I put the film type (such as Kodak Portra 160 ect.) into the metada?

I'm quite new with metadata and would be very happy if you could give me a hint !

Cheers =)