A Muqtadi making and Error

Q: Salaah-668: If a Muqtadi made an error while following the Imaam, should he perform Sajdah Sahw after the Imaam makes Salaam or not?

Answer: The Muqtadi need not perform Saydah Sahw. However, if he made an error while completing missed Rakaahs after the Imaam, Sajdah Sahw will be necessary. And Allaah knows best what is most correct.

Fatawa Rahimiyyah vol.2