need to modify resourcepool settings

i would like to modify the resource pool which contains my vms as below --  VM1,Vm2,Vm3 are in resourcepoolA - based on provisioned memory for the VMs Say $SUM=proviosioned_mem(VM1+VM2+VM3) --  i would like to reserve 25% of $SUM for the resourcepool

ideas?

Thanks,

~Sai Garimella