What is the maximum supported resolution of the MacBook Pro (Retina, 13-inch, Late 2013) for an external monitor at 60hz
Solution 1:
According to Apple's MacBook Pro (Retina, 13-inch, Late 2013) - Technical Specifications...
So it looks like 1080p is the 60Hz limit.
Solution 2:
I know I am late to this question, but I own the "MacBook Pro (Retina, 13-inch, Late 2013)" with "Intel Iris 1536 MB". I am currently using the macbook with the "Samsung SMS27A850" according to the system preferences it is currently running at 2560 x 1440 @ 60 Hz using the DisplayPort/Thunderbolt connection (not HDMI).