java.lang.ClassNotFoundException: oracle.stellent.ridc.IdcClientManager

IdcClientManager class is present in oracle.ucm.ridc-11.1.1.jar which is a part of RIDC JDeveloper Extension deployed as shared lib oracle.ucm.ridc.app-lib(11.1.1,11.1.1) on weblogic.

On the Project Technologies tab, select RIDC, which will automatically add the RIDC shared lib reference to weblogic-application.xml/weblogic.xml.

<library-ref>
    <library-name>oracle.ucm.ridc.app-lib</library-name>
</library-ref> 

Refer http://docs.oracle.com/cd/E23943_01/doc.1111/e10807/c23_ridc.htm#BABEIGAA