example: you have NAND cell with 2inputs A/B and output Z. you should:
RDC -from A -to Z
RDC -from B -to Z
when I verify a library. I do:
foreach INPUTs [list of all inputs] {
foreach OUTPUTs [list of all outputs] {
RDC -from $INPUTs -to $OUTPUTs > report.$INPUTs.to.$OUTPUTs.rpt
}
}