At this moment you need to have knowledge on how the IPTC profile is stored byte wise. You can set the profile like this:
I could add support for writing an IPTC profile.
using(MagickImage image = new MagickImage("YourImage.png")) { byte[] data = YourCreateIptcProfileMethod(); IptcProfile profile = new IptcProfile(data); image.AddProfile(data); }