A simple to way to add the record count to the output file in MPE/iX is to use the Echo command and the SuprtoolFullCount hpvariable. The only thing to remember is that the output file must have room for the extra line.
!job mgr.test !run suprtool.pub.robelle base store get m-customer numrecs 105% {build output bigger} set squeeze off {don't make limit = eof} output cust exit ! !file cust,old !echo Total number of customers = !suprtoolfullcount>> *cust !eoj