Zend certified PHP/Magento developer

Manually adding Searchable Words in PDF

Is there a way to add searchable tags/keywords to a PDF document?
I have heard of the OCR option in Adobe Acrobat, but for some reason this program keeps crashing, are there any alternatives?

Can this also be done manually? For example if the Document is a scan from a handwritten note, such that the headings could be searched?