That's not necessary. The financial institution will be sending a copy of the 2018 Form 1099-R to the IRS. Since a code P 2018 Form 1099-R does not report any tax withholding applicable to your 2017 tax return, there is no requirement to include a copy.
Your written explanation provides more detail than is present on a Form 1099-R. The explanation is normally sent when the tax return is originally filed and takes the place of the Form 1099-R that will generally not be produced by the financial institution nearly a year later.
