Unfortunately DMF is not available in Niran and QA team never went through this in past. I suppose Niran can not provide this docs. I am sorry. But I remember Niran has its FDA registration.
I talked to colleagues in Thailand, US, and Netherlands, they have clients as well from pharma industry, but DMF is not required for citiric acid. I had once a client in korea, they use it in tablets production, never required it as well.