Deductions & credits

In the online version I'm using, it says:

 

"When you prepare a substitute Form 1099-R, Distributions from Pensions, Annuities, Retirement or Profit Sharing Plans, IRAs, Insurance Contracts, etc., you are saying that the following statement is true:
I have been unable to obtain (or have received an incorrect) Form 1099-R, Distributions from Pensions, Annuities, Retirement or Profit Sharing Plans, IRAs, Insurance Contracts, etc., from my provider named X. I have notified the Internal Revenue Service of this fact."
 
So how does one notify the IRS of this fact, and if I'm looking to e-file and renew my info for stimulus purposes, and this year I can't claim a state tax credit based on the pension being on line 5, does it make sense to do form 4852 vs. reporting the pension income as "other income" on line 8?