How to deal with the AD7124-4 unused pins properly ?

Hi, 

I have read the AD7124-4 carefully but didn't find how to set the following 8 unused pins. Could you please give me the advice for each unused pin? 

1. pin3 CLK

2. pin18 --REFOUT

3. pin21 --PSW

4. pin9  --AIN1 

5. pin14 --AIN4

6. pin15 --AIN5

7. pin16 --AIN6

8. pin17 --AIN7

Thanks!