I found that Safari in Mavericks is not using local
proxy.pac at all.
Turns out because of sandboxing, it will not allow reading file from local.
A traditional solution is to turn on Web Sharing, and thus use HTTP to read the pac file such as
However, this cannot be done that simple, since Apple removed Web Sharing from normal version of Mavericks. To turn on the web service (Apache), do this:
Also, place the pac file under
/Library/WebServer/Documents, which is the default Document Root of Apache.
Tom Fischer proposed another way to get around, however I don’t think it a good idea to mess around the system files.