Two different things your asking here. If the money is already deposited in your account you have to take a proof of fund document from your bank. Just google this you’ll get standard format. Ask your bank to issue it
An affidavit is a completely different thing. It’s a legal document where your dad has to sign on a stamp paper stating he is responsible for your expenses. This has to be done from a notary. You’ll get this format also online. With this you have to attach all your financials in your dads name.
If the money has still not been deposited in your account and still with your dad, you can skip the first suggestion and just attach your dads account statement and the sworn in affidavit.
Hope this helps!