If you have made a Z copy out of standard program, Then pass the Z Program name in to 'POPUP_GET_VALUES_USER_HELP' Function Module like below. That will trigger 'CALL_F4_HELP' form in your Z program where you can the call of ' RSD_IOBJ_F4' depending on your requirement.
But this will not change the search help in Standard T-Code RSDMD. I'm sure you know about that.
CALLFUNCTION 'POPUP_GET_VALUES_USER_HELP'
EXPORTING
* F1_FORMNAME = ' '
* F1_PROGRAMNAME = ' '
f4_formname = 'CALL_F4_HELP'
f4_programname = Give your Z Program Name here
formname = 'POPUP_EXIT'
popup_title = text-001
programname = 'RSDMD_MDMT_WITH_F4'
* START_COLUMN = '5'
* START_ROW = '5'
* NO_CHECK_FOR_FIXED_VALUES = ' '
IMPORTING
returncode = l_returncode
TABLES
fields = l_t_iobjnm
EXCEPTIONS
error_in_fields = 1
others = 2.