AFE7950EVM: SYSREF Compatible Clocking Signal

Tool/software:

I would like to connect up the SYSREF input to a standard clock format but the input signal requirements fall outside of LVPECL, LVDS, CML, and VML standards.

If I look at the AFE7950EVM there are 100 ohm resistors in series at the clock source

and 100 ohm resistors to ground at the SYSREF inputs

I think this is intended to be a divider on an LVPECL output from the LMK04828 but if so it would fall slightly out of common mode specification. Could I get some guidance or confirmation on what clocking signal should be used here?

Thanks!