Transfer PDF from OS X to iPad
Use cloud storage like Dropbox, iCloud drive, or Google Drive and put your PDF files on it. I personally read and highlight Pdf files on an iPad app called GoodReader. With the app I can sync my highlight between Mac and iPad. The highlight from GoodReader shows on Mac OS X' Preview app without a problem, unlike Adobe Reader on iPad. If you read a lot of PDF then GoodReader is a worthwhile little investment.