This has become possible from RA78K0 V3.50.
Specification similar to the compiler using option -d is possible.
Perform specification as follows from the command line.
C> ra78k0 k0main.asm c054 -dSYM Or, C> ra78k0 k0main.asm c054 -dSYM=1
When performing specification with the Project Manager, input -dSYM or -dSYM=1 to "Other Options" on the "Other" page for the assembler option.