r xx.xx is the display of the output frequency F xx.xx is the display of the set frequency (00.00 to 400.0). Ie you will see the r xx.xx display increase to the F xx.xx number as it spins up.
What do you have PD001 and PD002 and PD003 set to?
If you want to control the VFD from the keyboard you need PD001 and PD002 set to zero
How are you setting the speed?
PS If the r 00.00 is flashing its when its not running and if steady its in run mode but you have no speed (frequency) set.