looking up your proposal again - which seems to be forgotten: please correct if i misunderstand:
You take an RDF/XML coded Scheme (which uses RDFS constructs - maybe along with other RDF/XML coded stuff)
and you want to provide RDDL metadata for it.
A human will just see literal content
rendered as XHTML. [The browser will ignore all tagging not in one of the W3C XHTML DTD's.]
What you assume the page looks to an RDF Parser - which graph it will see, when parsing the page?