In sap personas 3.0 Can we create a custom search help linking values from function module FI_F4_ZTERM

Good Day

I have a requirement as I have a custom field which is a zterm ( payment term ) on customer transaction. so it is  a search help field. but there is no

standard search help for zterm in knb1 table.  I have checked  in the standard transaction where the f4 help on the field  is linked to function module  FI_F4_ZTERM

I tested the function module and it gives a pop up with all values of payment terms and u can select the value from there.

is there a way i can do the same for this custom field.

I have created a field as f4 help in sap personas 3.0

I have a created a z function module as  rfc calling standard fm FI_F4_ZTERM

and I have done a scripting as below

var rfc=session.CreateRFC("ZFI_ZZTERM","");  ( calling rfc)

rfc.setParameter("I_KOART",'D');                      ( passing type as D)

rfc.requestResults(JSON.stringify(["ET_ZTERM"]));     (return the selected value from popup)

rfc.send();

var zterm=JSON.parse(rfc.getResults("Et_ZTERM"));

I think I am wrong in the sense as the function module gives a  popup as return and there is no data in ET_ZTERM.

until one of the value is selected on the popup.

but how could I get that popup when I click on my custom field search help? please suggest is my idea totally wrong.

thanks in advance

Regards

surendra