Most loc-tite bottles come with an applicator tip. They are exactly like a 'super glue' applicators. I find that when you use these with a fitting - they usually apply a nearly perfect 3-thread or 4-thread amount of loc-tite to the fitting.
Blue seems more runny to me than any other loc-tite. Simply add a drop toward the bottom of the fitting and usually it will run around the fitting and you can then simply put it on.
You don't need to overthink this. Simply add a drop - see how it looks - and add another drop if you need to.
Remember, with blue loctite - it does not need heat or any other thing to remove it. Also it doesn't seem to leave the kind of crystalline (plastic?) residue that red and green seem to. If you make a mistake, there is nothing wrong with taking it off - and simply doing it again.
Even if you had a solenoid in this marker - the blue would not flake off and get into the works. There is really nothing to worry about here.