Hi Mohan,
Please refer the standard component WDR_TEST_APPLDEF_VH1 which implements IWD_VALUE_HELP.
It has attribute VALUE_HELP_LISTENER of type IF_WD_VALUE_HELP_LISTENER in component controller.
You can get the attribute name for which F4 is triggered as below
WD_COMP_CONTROLLER->VALUE_HELP_LISTENER->IF_WD_VALUE_HELP_LISTENER~F4_ATTRIBUTE_INFO-NAME
Hope this helps you.
Regards,
Rama