Frequency Change In EVAL-ADF5355 Board

Hi, I purchased some EVAL-ADF5355 board recently. I. m using this driver to control my Electro optical modulator(EOM) at 9.2 GHz and now i want to do few changes in it. Firstly, i want to modulate the EOM frequency 9.2 GHz with 6 MHz and my second point is I need to change the rf frequecny(9.2 GHz) during the experiment in ms range. how do i do both of these. I'm not much expert in Rf. So, Please help me in figuring out this.

i used the P2 pin 1(VTUNE) to give the modulation and solder the 0 ohm bridge before R5. When I'm connecting the port to external modulation device my rf signal is getting jittery. It is genrating the sideband at 6MHz but signal is very jittery. can you help me out in this. Is this the correct way to do it or is there any other better option for it?