Statement of Physician question

Hi all,

I live in the United States and was treated last year for iron deficiency. I plan to self report this when I go to submit my application since part of my treatment plan includes yearly visits to a hematologist. Would I have my PCP fill out the statement of physician or my hematologist?

For those of you that had to have the form filled out, do you have a recommended way to go about it? Should I just print out the form and have them fill it out physically then scan it or should I use a service like Docusign?

Thank you!