I created my own font using my handwriting ($10, very easy) and auto fill my seller's names and addresses into a letter I typed in Word.

Do they have handwritten font but don't actually look handwritten?

Then you can split test your letter and see if you change the font, language etc.

From what I have read you are on the right track, I have heard that using yellow lined paper and a "handwritten" font on your letters as well as handwriting the addresses on the envelopes also helps increase the probability of  a response.  

The only thing with PDF is that they won't allow you to adjust the font size if reading on the kindle, which tend to be very small.

The law goes so far as to require the size of font for some statements.

I'm kind of a typography nerd, as stupid as that sounds, and I've never seen this font before.

Section 57 of Bill 1502 was enacted the end of June and requires landlords to include a notice in every residential lease in “not less than 12 point boldface type in uniform font” Disclosing whether or not the dwelling unit they are renting has a working fire sprinkler system.

White card, black lettering, simple clean font, my name, email, snail mail, and phone number. 

I have a handwritten font of my handwriting that i print back on the paper.