This is an example of Test Result RDF document through QM OSLC API.
Make sure you specify this headers to get the content
accept : application/rdf+xml
OSLC-Core-Version: 2.0

<?xml version="1.0" encoding="UTF-8"?>
<rdf:RDF
    xmlns:dcterms="http://purl.org/dc/terms/"
    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:rqm_auto="http://jazz.net/ns/auto/rqm#"
    xmlns:calm="http://jazz.net/xmlns/prod/jazz/calm/1.0/"
    xmlns:rqm_qm="http://jazz.net/ns/qm/rqm#"
    xmlns:acp="http://jazz.net/ns/acp#"
    xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
    xmlns:foaf="http://xmlns.com/foaf/0.1/"
    xmlns:oslc_auto="http://open-services.net/ns/auto#"
    xmlns:oslc="http://open-services.net/ns/core#"
    xmlns:oslc_qm="http://open-services.net/ns/qm#"
    xmlns:bp="http://open-services.net/ns/basicProfile#" >
 <rdf:Description rdf:about="https://myrqmserver:9443/qm/oslc_qm/contexts/_0I6VT9HVEeGSWYp6WoHgWA/resources/com.ibm.rqm.execution.ExecutionResult/_hjYFQyRaEeK7qas16_dx7g">
  <oslc:instanceShape rdf:resource="https://myrqmserver:9443/qm/oslc_qm/contexts/_0I6VT9HVEeGSWYp6WoHgWA/shape/resource/com.ibm.rqm.execution.ExecutionResult"/>
  <oslc:serviceProvider rdf:resource="https://myrqmserver:9443/qm/oslc_qm/contexts/_0I6VT9HVEeGSWYp6WoHgWA/services.xml"/>
  <dcterms:title rdf:datatype="http://www.w3.org/2001/XMLSchema#string">Lyo</dcterms:title>
  <oslc_qm:executesTestScript rdf:resource="https://myrqmserver:9443/qm/oslc_qm/contexts/_0I6VT9HVEeGSWYp6WoHgWA/resources/com.ibm.rqm.planning.VersionedExecutionScript/_n7DsYBoPEeKFULkQmjVzFg"/>
  <rqm_qm:verdict rdf:resource="http://jazz.net/ns/qm/rqm#com.ibm.rqm.execution.common.state.passed"/>
  <rdf:type rdf:resource="http://open-services.net/ns/qm#TestResult"/>
  <oslc_qm:producedByTestExecutionRecord rdf:resource="https://myrqmserver:9443/qm/oslc_qm/contexts/_0I6VT9HVEeGSWYp6WoHgWA/resources/com.ibm.rqm.execution.TestcaseExecutionRecord/_sLIr-CRLEeK7qas16_dx7g"/>
  <oslc_qm:reportsOnTestCase rdf:resource="https://myrqmserver:9443/qm/oslc_qm/contexts/_0I6VT9HVEeGSWYp6WoHgWA/resources/com.ibm.rqm.planning.VersionedTestCase/_tK7qkRoPEeKFULkQmjVzFg"/>
  <acp:accessControl rdf:resource="https://myrqmserver:9443/qm/oslc_qm/accessControl/_0I6VT9HVEeGSWYp6WoHgWA"/>
  <dcterms:created rdf:datatype="http://www.w3.org/2001/XMLSchema#dateTime">2012-11-01T19:29:59.188Z</dcterms:created>
  <dcterms:relation rdf:resource="https://myrqmserver:9443/qm/service/com.ibm.rqm.integration.service.IIntegrationService/resources/_0I6VT9HVEeGSWYp6WoHgWA/executionresult/urn:com.ibm.rqm:executionresult:481"/>
  <dcterms:modified rdf:datatype="http://www.w3.org/2001/XMLSchema#dateTime">2012-11-01T19:29:59.266Z</dcterms:modified>
  <dcterms:identifier rdf:datatype="http://www.w3.org/2001/XMLSchema#string">https://myrqmserver:9443/qm/oslc_qm/contexts/_0I6VT9HVEeGSWYp6WoHgWA/resources/com.ibm.rqm.execution.ExecutionResult/_hjYFQyRaEeK7qas16_dx7g</dcterms:identifier>
  <oslc_qm:status rdf:datatype="http://www.w3.org/2001/XMLSchema#string">com.ibm.rqm.execution.common.state.passed</oslc_qm:status>
 </rdf:Description>
</rdf:RDF>

It iis discovery based process, you always starts with rootservices URL and then discover the URLs
e.g.
1. https://myrqm:9443/qm/rootservices
Look for oslc_qm:qmServiceProviders in it to get qm catalog URL
2. Open qm catalog URL e.g. https://myrqm:9443/qm/oslc_qm/catalog
Use header
accept : application/rdf+xml
OSLC-Core-Version: 2.0
3. Response contains a list of service providers, essentially each service provider is a project area. Pick any one, there will be a URL which ends with service.xml
e.g. https://myrqm:9443/qm/oslc_qm/contexts/_0I6VT9HVEeGSWYp6WoHgWA/services.xml
4. Open service URL
You will get URL for all resources, Creation URL, resource shape URL, resource query URL etc..
e.g.

<oslc:queryCapability>
                    <oslc:QueryCapability>
                        <dcterms:title>Default query capability for TestResult</dcterms:title>
                        <oslc:queryBase rdf:resource="https://myrqm:9443/qm/oslc_qm/contexts/_0I6VT9HVEeGSWYp6WoHgWA/resources/com.ibm.rqm.execution.ExecutionResult"/>
                        <oslc:resourceShape rdf:resource="https://myrqm:9443/qm/oslc_qm/contexts/_0I6VT9HVEeGSWYp6WoHgWA/shape/query/com.ibm.rqm.execution.ExecutionResult"/>
                        <oslc:resourceType rdf:resource="http://open-services.net/ns/qm#TestResultQuery"/>
                    </oslc:QueryCapability>
                </oslc:queryCapability>
                <oslc:queryCapability>

I have similar kind of problem.
I have added the header :
accept : application/rdf+xml
OSLC-Core-Version: 2.0

but still its reading it in text/html.

Can anyone help me.