can Thick client be helpful in getting the IDs of the custom sections that are created from inside RQM Test Case Template?

You can get the feed to all of the templates by using this URL in the browser

https://clm401:9443/qm/service/com.ibm.rqm.integration.service.IIntegrationService/resources/CLM_LCP+%28Quality+Management%29/template

In this example, the public URI is 'clm401:9443' and the QM project is 'CLM_LCP (Quality Management)'

This will give you a list of all your templates; find the one being used for Test Cases, right click and select 'Copy Link Location'. Use this URI in Poster or some other HTTP client and perform a GET; it will return the XML of the artifact

Once you obtain the response back from Poster you should see the custom section listed in the XML

<ns2:section name="RQM-KEY-TC-SCRIPTS-TITLE" id="com.ibm.rqm.planning.editor.section.testCaseScripts" description="RQM-KEY-TC-SCRIPTS-DESC"/><ns2:section name="RQM-KEY-TC-SUMMARY-TITLE" id="com.ibm.rqm.planning.editor.section.testCaseSummary" description="RQM-KEY-TC-SUMMARY-DESC"/><ns2:section name="RQM-KEY-TC-NOTES-TITLE" id="com.ibm.rqm.planning.editor.section.testCaseNotes" description="RQM-KEY-TC-NOTES-DESC"/><ns2:section name="MyCustomSection" id="com.ibm.rqm.planning.editor.section.dynamicSection_1368535206438" description="CustomSection"/></ns2:sections></ns2:template>