RAD doesn't have this option.
Go to the site
http://www.ibm.com/developerworks/websphere/library/techarticles/0601_patil/0601_patil.html
Download the war files as per instruction. Import the SPFStandardBlank.war in RAD. SPFStandardBlank.war is a blank struts JSR 168 portlet project. Develop your application on top of this blank portlet.
Hope this helps.