In N3 and RDF+XML you /can/ refer to the current document as a zero-length-string-URI. eg. "" or <>. This is not recommended. If possible refer to the document it's authoritative URL. That way if it gets saved to disk and reloaded it doesn't then end up with it's URI/URL being its new filename.
<rdf:Description rdf:about=""> </rdf:Description>
<rdf:Description rdf:about="...URL-of-RDF-Document..."> ... </rdf:Description>
License & Rightsholder
At the very least you need to include a license. Without a license, your RDF is not Open Data.
Express the license using DCTerms:
<dct:license rdf:resource="...LICENCE-URI..." />
You may also add "dct:publisher" and "dct:rightsHolder" to link to the URIs of the publishing and rights-holding organisations (will often be the same, but not always). It is recommended that you also use an rdfs:label to give these organisation URIs a human readable label.
Not all licenses are suitable for use with data. The following are (nb. I am not a lawyer...)
More information on open licenses is available at http://www.opendefinition.org/licenses/
The following are the recommended URIs to use for RDF data.
If the RDF triples in a document are also available from a SPARQL endpoint then you can add the following relation to the boilerplate.
<void:sparqlEndpoint rdf:resource="...URL-of-SPARQL-Endpoint..." />