as usual the Rob is right. -v shows load factor:
$ ischk ischk ------- PRO-IV (R) Verify internal structure of PRO-ISAM files Copyright (C) 1999 PROIV Technology, Inc. All rights reserved. Unauthorised use strictly prohibited. PRO-ISAM Version: 13.04.15.01S Date: Mar 17, 2000 usage: ischk {-s} {-nyv} filename(s) options; -s Suppress the Copyright banner. -n Automatically answer N(o) to 'Repair File' -y Automatically answer Y(es) to 'Repair File' -v Verbose mode. Report page allocation and load factor filename(s); One or more PRO-ISAM files seperated by spaces.