Search Help Exit

Dear Experts,

I have a requirement in which I have to put certain validation in F4 help in Customer field in XD03.

But the thing is when I see the field name in XD03 screen by using F1 and tool tip it says RF02D-KUNNR (RF02D is a structure) and when i see the

field KUNNR of RF02D there is no search help at data element level.. and when i see KUNNR filed in SE11 it does contain a search help C_KUNNR..

KUNNR in RF02D have a different data element and KUNNR when seen in SE11 have a different data element.

So I want to as that in which field do i have to implement search help enhancement i.e. on RF02D-KUNNR or on KUNNR (As the both have a different data elements)..

Thanks in advance..

Regards,

Paavan