I'm not sure how much is recommended but I'm sure a google search will handle that.
I personally supplement with a fiber powder every morning in my shake. I was very gassy at first while my body adjusted but after about two weeks I seemed to be not as gassy and I'm much more regular. On occasion I have added in a second dose at night but that seems to be too much for me at least. Start at a low dose and see how you react then adjust from there.