The startup script is envoked by your profile ($home/lib/profile)
where it starts rio (I call mine startup, you seem to call yours
riostartup, its personal choice really)
here is the relevant line in mine:
exec rio -s -i startup
and here is my $home/bin/rc/startup
#!/bin/rc
auth/fgui &
if(~ $service terminal)
window -r 0 0 200 120 stats -lmei $sysname $cpu
if not
window -r 0 0 200 120 stats -lmei
window -r 201 0 845 120 faces -i
window -r 1159 0 1279 120 clock
window -r 95 212 921 734 logwin
The last line above starts logwin which is a seperate script which
opens my first terminal window and runs fortune etc in it, here is
$home/bin/rc/logwin
#!/bin/rc
fortune
calendar -y
news
echo
exec rc -i
-Steve