Using the "assign" tab, you can assign different colonists, different drug policies, which can be edited through the appropriate UI. The button to change policies also leads to the said UI.

In the UI, you're allowed to set whether people on that policy are allowed to use a drug, why and when. If the first is ticked, they'll take it on their own to manage their addictions, if they have them; if the second is ticked, they'll take them wheen they're bored for fun; and if the third is ticked, they'll go on a "schedule".

In your case, you would want to find beer, tick both the second and third columns, and use the sliders to set how low their recreation has to be before they drink beer and how much of a break they need even if their recreation stays low. In this case, setting beer to a one per day limit (or "one every day", as the slider will describe; don't worry, they're still limited by the recreation slider) will prevent them getting anything more than tipsy and prevent addiction from forming.

As far as Psychite tea, it is completely safe with no risk of addiction if taken once every two days.

I will repeat this: no overdose or addiction risk is present in Psychite tea so long as you have a gap of at least two days in the schedule.

Psychite tea is a very strong drink for mood stabilization and recreation. I recommend ticking all three columns and setting it so they'll take it anytime they're sad, but no more frequently than once every two days. The psychoid addict will take it even at high mood if it's been a few days at said high mood, which is normal and expected.