Q: Problems sending a fax pdf from iMac OSX Yosemite.

The menu only shows up in the PDF menu if you have a fax printer selected in the Printers menu. Do you have a fax printer installed and selected? And you're looking at the PDF menu, not the Printers menu?

I'm having the same problem.  I have an Epson Workforce 545 All-In-One.  It is set up as a fax machine.

Click on "Layout" for a popup of options. Read your user guide or search the Epson website. For instance, see Sending faxes using the fax utility - Mac OS X.

Thank you LilyLC!  Clicking "Layout" opened recipient options.  Couldn't find it in the link or anywhere else I looked.

Your welcome, istbo1313! Thanks for posting back as it may help the OP and others.

I'm having the same problem but I can't solve it. Where I can find "Layout"?

Look at the screen shot above that itsbo1313 posted. That screen shot shows that itsbo1313 was using Apple Pages application. Different applications might have a different list order. In the same place as "Location" it could be "Copies & Pages" or the application name, e.g., Safari, or something else. Just click on it for a popup list of options.

The support page OS X Yosemite: Send a fax makes it sound like all you have to have to send a fax is a computer and a modem. It makes no mention of needing a printer that just happens to have fax functions.

I have a printer that is not a fax machine. I don't get any fax options in my drop down menu, either.

I am looking for a way to send a fax directly from the computer. 

I am looking for a way to send a fax directly from the computer. 

Launch the App Store and search for fax. There are a number of apps. Alternatively, there is efax.com and myfax.com.

HTH

The support document makes it sound like you don't need an app. So, what you're saying is that you actually do/that the support doc creates the wrong impression?

Based on your original post, you stated that "I have a printer that is not a fax machine" and I assume that you do not have a fax modem that is compatible with Yosemite; yet, you still want to "fax directly from the computer."

Internet faxing via services such as efax.com and myfax.com do not require any apps.

The Apple article states:

"Note:   The following provides instructions for printing using the standard features in OS X and may not match your setup. If these instructions differ from the user interface you’re seeing, refer to the documentation that came with the app [emphasis added] you’re using."

The Apple article states:

If your Mac has a modem connected to a phone line, it’s automatically configured to send faxes.

That's the part that I'm questioning. 

"You can fax files directly from your Mac to any fax machine or computer that’s set up to receive faxes [emphasis added]."

Is your computer is set up to receive faxes?

You can submit your concerns to Apple - Feedback.

Yes, of course, the other computer is set up to receive faxes.