with a structure of RKF1, RKF2 and RKF3, there is no way to limit the account rows like you would like to. Even the zero suppression doesn't work because the structure element in the row is not treated as a blank.
I am assuming the example you gave is just a sample and the data is actually more complicated. If not, you are better of creating selection for each account and placing them as subnodes of RKF1, 2 and 3.
If it is more complex and all you are doing is grouping accounts, you may think of creating a hierarchy on account manually in RSA1 and using the hierarchy for reporting