Generally you dwell at the frequency and G level that the device will be attached to (i.e. planes, ships, trains…) and not necessarily at the Fn of the unit. This will show that the device will function correctly on whatever you are putting it on. However, this method is very old. These days, it’s best to use random vibration where all frequencies are excited instead of one frequency. I must of missed it, but what is your application? If for Environment Stress Screening you may want to take the g level down by 1/3rd . If you are doing a prequalification test, you may want to take the g level up by 10 to 20% to gain margin.
Tobalcane
"If you avoid failure, you also avoid success."
“Luck is where preparation meets opportunity”