We have a 1099R from my previous employer showing a gross distribution. they mailed me a check and the money was sent directly to Fidelity Innvestments. How do i prove?

For the tax return, you only need to indicate the rollover and amount (20% is required withholding but to not be taxed you must have funded the new account with the total amount).  The IRS will receive the information about the contribution from the new retirement account.