You want the total exposure for each bit of paper to be the number from the sequence, so (assuming you're doing the covering-up thing) each exposure is the difference between respective steps: 2.8, 4-2.8=1.2, 5.6-4=1.6, 8-5.6=2.4, 11-8=3, 16-11=5, 23-16=7, 32-23=9.
I think I get the gist, but with linear intervals, I set my timer on the time, then slide a sheet from one side of the print to the other. How do you do that with fstop printing? If I added 5.6 seconds on top of the 8 second, that would give me 13.6 seconds. I would have to cover that 8 second portion right?