a good way to measure out small amounts like that is to get get a syringe(27g is fine) that is measured in IU, the syringe will look like this and will be 1mL
when you get home you can take the needle off(might have to use pliers depending on the syringe) and measure that way
100IU=1mL
so 20IU=1/5 of a mL
so with your concentration
100IU=200mcg
75IU=150mcg
50IU=100mcg
25IU=50mcg
basically, figure out what dose you want to take, say 80mcg, and divide that dose in half, this is the amount of IUs you will take(this only works for 200mcg/mL)
then just take off the top to your clen, draw the amount you need, and squirt it in your mouth