John, you may want to check with the documentation for
sml:ConvertRDFToXML, which I will repeat here:
"Converts RDF into XML using the Semantic XML (sxml) ontology for the
round-tripping. The resulting XML will be bound to the specified
output variable. Note that this requires the RDF model to contain an
SXML root document element - this function does not work with
arbitrary RDF data! For more, see Help > Import and Export >
Creating, Importing, Querying, Saving XML documents with Semantic
XML."
For more on the format the RDF data needs to be in, see documentation
on Semantic XML (Help > Import and Export
Creating, Importing > Querying, Saving XML documents with Semantic
XML)
If you are looking to save your data in RDF/XML, then just specify
a .rdf file in the sml:ReturnRDF or sml:ExportToRDFFile module.
-- Scott