A Resource is what we call a Record that has been downloaded from the site and used in a Remix. These can be cited in the Record Contribute form. You can cite as many resources as you like so long as they have been used in the final Remix. It's very important to only cite Records that were used in the final Remix so that collaborators are accurately cited for their work so when the time comes for payment, everyone involved gets their fair share of reimbursement!
If you have any further questions, please reach out to Support via Support@hitrecord.org and we will be happy to assist you!