Instead of a password protected pdf, there are several secure sites that you need to use a password. McAfee and Watch Guard are 2.
They are directors and should be aware. I would have the CEO make sure they are aware, and provide them with cross-cut shredders that turn the paper into confetti. (You may also want to check on the bank's blanket-bond policy to make sure it covers them.)
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Integrity. With it, nothing else matters. Without it, nothing else matters.