want to sign multiple documents with multiple signatures

[codi modi]

hey there 

I am having a problem. lets say I have 100 pdf documents, 2 pages each. I need to sign them with 100 different signatures, each signature is for a certain document. I have all of the signatures ready in png format on my hard drive. I need to do it with an automated kind of process. like batch processing or something like it. please help me with this . the actual number of documents which need to be signed is more than 1000 ! So I cant do it manually and I need to do it like a automated process. 

thanks for your help