Hi,
you can set pf status in se41 tcode.
OR
in your module pool program use statement
set pf-status 'zabc'.
double click on zabc it will allow u to create pf status.
In module pool screen, you can define 'ENTER' fuction code in the pf status of the particular screen. It can be given in the 'Function Keys'.
We can capture the f-code by using the system variable sy-ucomm .