Reviewing the schema documentation, the XMP template needs to be updated in the 
following ways:

1) We need to use xmpRights as the RDF prefix for the XMP Rights schema (I believe 
this has changed in the XMP spec over the years).
2) We need to replace or supplement dc:rights with xmpRights:UsageTerms, as the 
schema documentation indicates this is human readable text for how the resource 
may be used.