What modifications to the EXTFH.CFG file would be necessary to use just MF (Micro Focus) format file creation and file handling. 

The current configuration file Contains RM and ACU formatting and handling :

[XFH-DEFAULT]
FHREDIR=OFF
ACUFH=ON
ESACUFH=ON
CONVERTSTATUS=rmstat

INDEXCOUNT=32
STRIPSPACE=OFF
DATACOMPRESS=1
KEYCOMPRESS=15
IGNORELOCK=ON
RETRYOPEN=ON

INTEROP=

[SEQ-DEFAULT]
SEQDATBUF=8192

[REL-DEFAULT]
RELFORMAT=MF

[FOLDER:/]
INTEROP=

[FOLDER:/MNG1/EXPL/PAN]
INTEROP=RM
[FOLDER:/MNG1/EXPL/FICH/RM]
INTEROP=RM

Full article: https://portal.microfocus.com/s/article/KM000017492