Connecting external clock

[dunlikecoding2]

Hi, is there any code modification required to connect external clock from function generator?
In terms of code, I have change to AD5933::setInternalClock(false).
In terms of hardware, I removed the LK3 connection and connect LK4.
With these changes, the code doesnt run, please advise what is the correct steps to connect external clock.
Thank you.