How do I set up synthetic drone reeds?
Let me preface by saying that not all drone reeds are "ideal" with all drones. Some drones tune way too high with some brands of reeds. Some drones are very "rough" with some brands of reeds. I recommend that you talk to others with your brand of pipe and get a recommendation.
First off, do not ever TOUCH the tongue of any "modern" synthetic drone reed. No hairs, no credit cards, no knife blades. Don't touch it.
Keeping this in mind, you need to first adjust your new reeds to the air needs of your pipes. For most modern brands, you'll only need to adjust the bridle to set the air consumption. You should just be able to "blow out" a drone reed by blowing really hard - don't give yourself a hernia! - but it should "shut down" at very high pressure. If not, it's too open and you're wasting energy that you could put into playing.
Remember that most reeds will become more pliable with temperature, so play for a minute or two to warm up the reed. Then set so that it will just barely shut off when you blow really hard by adjusting the bridle up or down in millimeter increments. If you get tired in this process, you may have to tweak it again tomorrow, but make very small adjustments.
Once the air flow is right for your drone/reed combination, then move the screw/plug to get the drone to tune to the right spot on the hemp for your chanter.
At this point, you are done.
(Note: If you can't get a bass drone to tune in a reasonable range with a particular of reed, be aware that some reed makers can provide long and/or short bass drone reeds.)