# dtx file: how to run it?

I want to clarify first that I am a beginner, and thus my question might be imprecise or inadequate. Anyway:

I found this documentation file for the package microtype, can be easily found on ctan. It is microtype.pdf. I like the format of the document and the font of the document, so I downloaded the .dtx file and try to see how they got it. Of course, I cannot understand almost anything about the code. Anyway I try to compile it with pdfLaTex. But this does not work, as a series of errors and warnings appear.

I report the last lines of the log file, if they are useful

[1{C:/Users/User/AppData/Local/MiKTeX/2.9/pdftex/config/pdftex.map}
! pdfTeX error (font expansion): auto expansion is only possible with scalable
fonts.
\AtBegShi@Output ...ipout \box \AtBeginShipoutBox
\fi \fi
l.767 %\newpage

!  ==> Fatal error occurred, no output PDF file produced!
Transcript written on microtype.log.
texify: pdflatex.exe failed for some reason (see log file).

• Welcome to TeX.sx! Ususally the first error is the important one (at least the first one should try to solve...) – clemens Oct 18 '13 at 19:24
• – Martin Schröder Oct 18 '13 at 21:44

microtype.dtx uses the EC fonts (=Computer Modern in T1 font encoding). You need to install the scalable Type 1 variants. They are available as cm-super. Install it with the package manager.
First the answer to your initial question: the document uses Bitstream Charter as the main font, Bitstream Letter Gothic for the code, and (in the latest version) Adobe's Source Sans Pro for the sectioning. There are several methods of finding out which fonts are used in a PDF document, even without looking at the source code. But if you do want to look at the code, you'll find that the fonts are set shortly after the exclamation "Let's abolish CM!"
The errors you get are probably caused by a missing font. Martin has already given you a link to the relevant question, I especially recommend Ulrike's answer for finding out which font is missing on your system. (Charter and Source Sans Pro are available on CTAN, for Bitstream Letter Gothic - which AFAIR is not – you could use URW Letter Gothic as a replacement, by changing the line \def\ttdefault{blg} into \def\ttdefault{ulg}.)
EDIT: Note that I am referring to the latest version (2.5a). In previous versions, the font switching commands were commented in the dtx file, so that compiling it at home would use the EC fonts (as @Heiko says), while the pre-compiled pdf still featured Charter and Letter Gothic.