In Logikcull you can add Notes to any document through the Notes box on the Document Information pane. Simply click the Document Info tab to expand the Notes box and type away!
Be sure to click Save Notes when you're done in order to save your changes.
Document Notes can both be searched from Advanced Search option (using the Logikcull Document Notes field), or from the main Search bar with a fielded query beginning with:
followed by the text you'd like to search.
You can export your Notes when creating a download by selecting the Logikcull Document Notes field in your download template.
Finally, you can find documents in your set with Notes applied to them by searching for the "Has Notes" tag.