RDF resource as Dublin Core's <source>

Hi,

Thanks for the great module! It gives so much control over feeds that it satisfies any admin.

I'm missing one feature: giving item's sources as URL instead of free text. In order to do that field's contents should go to rdf:resource attribute instead of tag's value. On site I'm developing there is a link field (could have multiple values) pointing to source of material from which I can extract URL as a plain text (using link field's formatter). I would love be able to somehow tell Views RSS to put it as an attribute in the output. It could be done automagically, just by looking if the given field contains a valid URL.