latest code on SVN contains support for setting the duty cycle of Fout, from 0 to 100 (in 5% steps):
svn checkout http://dsonano.googlecode.com/svn/trunk/DSO_BenF_v3_IAR5 dsonano
On first downloading the firmware, you might find the Out Duty is uninitialized - it happens if you have ever saved your profile to flash, since the the newly introduced OUTPUT_DUTY parameter will be missing from your existing profile.
I will try to fix this ASAP, for the meanwhile you can keep BtnRight pressed until you get a correct value (between 0% and 100%) - it will take a few moments. As soon as you get to 50%, simply save your profile again to flash.
EDIT: added a DFU file with the changes
dso-svn-r17.zip (25.6 KB)