Excerptor

Excerptor lets you take and locate excerpts in PDF files quickly. When you read a PDF file, you may want to take some excerpts, like excerpting on physical books (including article name, page number, etc.).

Via Excerptor, you can take excerpts easily: select text in Preview/Skim and type a shortcut. An excerpt will be stored in the pasteboard or in a file. The excerpt includes a special link. By clicking on the link, Excerptor will open the corresponding file by Preview/Skim, go to the page you want and highlight the excerpt you made, automatically.