Since you are new to psrchive, I will recommend you use psrplot instead of pav. It's much more flexible. To get the same plot you would run 'psrplot -pY -j F out.ar'
psradd does not support any '-f' option, unless you are running some very old version which does. In any recent version you choose the name of the output file using 'psradd -o out.ar files*.ar'
Could you post the output of :
psredit -c nsubint,length,int:duration out.ar files*.ar