Most growers ignore VPD and just keep RH around 40-45% in flower to mitigate mold risk.
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You measure your VDP according to specs below. It looks like your VDP is 1.24 and your in flower. Seems ur in the range. Keep your temps between 68F and 79F, RH between 40-50%.
I think I can do that! Is it ok to let it dip to the upper 60’s at lights off ? Currently 18/6. Thanks!
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Perfect flower temp 
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I play with temps when outside temps allow it 
It was freezing outside so i gave the bus the ole shock a roo…
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Vdp control for most growers is really not possible for many reasons. The biggest one is sensor calibration and sensor drift.
Most temp sensors are accurate to ± 3% So when you app says 73 degrees it could be 71 or 75. Rh is better at ±1 % so within a point. Then there is the laughable leaf temp difference. You use a resistor type sensor for one input and a IR tool for another input. How did you zero them?
Most hydro growers calibrate PH as a maintenence item. I do the same for my temp and humidity sensors when I put everything in the same place at the same time and calibrate and I still do not fuss over VDP. The range of acceptable temps and humidity is very broad for cannabis. Keep in the lanes and you will do fine.
Now go calibrate your sensors with a good quality gauge set.
Imo you’re better off chasing your leaf surface temp and then using vpd as a guideline as to where you should attempt to get RH. Most of us don’t or can’t get to a prefect vpd, but getting too far out of line can cause some issues.