Which attribute to use for marking files "reviewed"

What I am trying to achieve:
I am trying to set up a paperless workflow using Hazel. So far the files get properly renamed by Hazel (yeah, magic!). Before I let Hazel file the documents, I want to review the documents (credit card statements and such). Now I am looking for a simple way to mark the document as "reviewed".
I thought: open all documents that need reviewing in Preview, review them and add a "reviewed"-tag via a keyboard shortcut, close Preview and let Hazel work its magic. However, I can not figure out how to assign a keyboard shortcut to adding a certain tag from within Preview.
Do you have ideas what other attribute I could use to tell Hazel, that this document is ready for filing? I would like to do the reviewing in Preview and have a hotkey to assign this attribute. But in the end I am grateful for anything that might streamline the process
I am trying to set up a paperless workflow using Hazel. So far the files get properly renamed by Hazel (yeah, magic!). Before I let Hazel file the documents, I want to review the documents (credit card statements and such). Now I am looking for a simple way to mark the document as "reviewed".
I thought: open all documents that need reviewing in Preview, review them and add a "reviewed"-tag via a keyboard shortcut, close Preview and let Hazel work its magic. However, I can not figure out how to assign a keyboard shortcut to adding a certain tag from within Preview.
Do you have ideas what other attribute I could use to tell Hazel, that this document is ready for filing? I would like to do the reviewing in Preview and have a hotkey to assign this attribute. But in the end I am grateful for anything that might streamline the process
