Q: How do I print return labels in Contacts?

what do you mean with "return Labels"?

Contacts – Print Contact Information

Contacts (Yosemite): Print labels, envelopes, and lists

How do I print return labels with the Apple Contacts application?

I will try to give you a workaround:

1) select the one card you want to print many times

2) call the print dialog and let configure this: Styling > Page > DYMO - Shipping Labels (you must see your contact size filling on the Demo-Page-Format)

3) don't print, let only open as PDF in preview an let you show the thumbnails (cmd+alt+2)

4) do this another time, so that you have two open PDF with you label with thumbnail (on the left)

5) drag so many times (5, 8 or 15) one thumbnail on the other open pdf so that you have the right number of "pages" that you want to print on your A4 (or US Letter).

6) now you have i.e. a PDF with 9 identically pages and you can print from PDF choosing in layout "print 9 pages per Sheet)

7) Enjoy cutting your labels