LMR36510: Margining the LMR36510 with external DAC

Tool/software:

Hi,
I am using LMR36510 for our application. 
Vin = 24V, Vout = 12V, Iout = 0.015mA. 

I need to margin the output voltage via external DAC. May be +30% to -30%. 
Could you please tell me, how can I connect the DAC output in order to change the Vout of the LMR36510? 

I am attaching the circuit which I used

And also, please suggest a voltage DAC for margining it

Thanks