Yes, you can convert a CFI flash memory .pof for PFL to a .rbf.
If you use the PFL to configure an FPGA and store configuration data to CFI flash memory by an external CPU or flash ROM writer, not by PFL, you need to make a .pof file for Fast Passive Parallel (FPP) or Passive Serial (PS) first and convert it by the following mothod:
1) Convert .pof to .hexout using the following command line.
quartus_cpf -c <pof_file_base_name>.pof <hex_file_base_name>.hexout
2) Convert .hexout created in (1) to .rbf using the nios2-elf-objcopy command on Nios® II Command Shell.
nios2-elf-objcopy –I ihex –O binary <input file>.hexout <output file>.rbf
For more information on the nios2-elf-objcopy command, refer to NIOS II Command-Line Tools (PDF).