You can move the whole amount and separately send in an estimated payment to cover the tax. That way it all gets moved to the ROTH. Or if you have withholding taken out you can replace it by depositing other money into the ROTH within 60 days. Either way.
Here are the current 1040ES instructions and blank forms (where to mail is on page 4)
https://www.irs.gov/pub/irs-pdf/f1040es.pdf
Or you can pay on the IRS website. Be sure to pick 2025 1040ES payment
https://www.irs.gov/payments
