Former pre-press anon here. I have examined the PDF of the Blasey-Ford letter to Feinstein. The first line of text in the body appears to be the same font, but is stretched vertically by approximately two pixels. The rest of the text appears to be consistent.
It is difficult to examine this for forgery/editing because it is definitely a scan. There are no extra layers or anomalies in the way the file is built as far as I can tell. The only layers in Adobe Illustrator are a clipping path container for the raster image that comprises the scanned bitmap image. Essentially, this is a copy of a copy, but I don't see anything that screams that the file has been tampered with in any way.
The stretching in the first line of text could potentially be a scanning artifact if it was scanned through a document feeder, as opposed to a flatbed scanner.
I have no reason to believe the file is faked or tampered with, though the first line in the body does look a bit off. However, the name "Kavanaugh" appears throughout the body copy and (with the exception of the first line) appears to be consistent with the typeface, printing, and imaging throughout the rest of the document.
Unfortunately, that's all I've got unless someone can provide an original digital file.
This is the file I examined:
https://www.judiciary.senate.gov/imo/media/doc/2018-09-20%20Feinstein%20to%20Grassley%20-%20July%2030%20Letter%20from%20Ford.pdf