In the long run, you should DEFINITELY get a scale.. The difference between 2-6g rue (or between, say, 3 to 9g mimosa) is very big in terms of effects, and it might make the difference between just enough alkaloids, to a very high dose and unpleasant trip...
In any case, just for the sake of harm reduction, i made this thread regarding mimosa estimation:
and regarding rue, I just measured and
my teaspoon (
teaspoon, not normal spoon) was around 2-4g rue depending on how much I filled it... so a teaspoon should be around a dose of rue. It might be your teaspoon is bigger, or smaller... Definitely dont take more than a teaspoon of rue.
And please, buy a scale, it will be very useful ! You can get some quite good ones for 30 bucks.