Adolbe Acrobat Pro says file corrupted

Hello to all those smarter than me. I'm having issues with Adolbe saying my files are corrupted.My files are documents that I wrote(affidavits) in Libre Office and they are not corrupted. I can make them into a PDF and adolbe recognizes them. I don't want them in PDF,I need them in rtf just like I wrote them and I needb to sign themand not make a secure unchangable document of them. Can anyone tell me what is wrong and how to sign documents without the secure setting? I loose more valuable time than I get work done trying to get answers. Thanks to all Sincerely Kyle Jennings