I am using AD9467-FMC-250EBZ with ZedBoard. The reference design works with 250 MHz external clock.
The ad9265-fmc-125ebz board has some commen points with mine.The default clock path is the external clock. And you can reference AD9265 Native FMC Card Reference Design [Analog Devices Wiki]
The ad9265 will be drived by the default clock path, and the demo project will work fine. Then you can read the ad9265 datasheet to set the registers making it work in the mode you want.