If that's the type I'm thinking about, there should be a completion bar on the path window under the quest, which fills up as you get closer to the exact spot you have to stand on. Once you're there, you can click a button at the end of the bar to activate whatever it is. For settler at least there were many quests like that during beta where you'd need to find hidden caches and shit and you had to stand on the right spot, click the button and the cache would pop and complete the quest. The button wouldn't show unless you were on top of it, and it only showed on the path tracker itself which most people missed, shit was confusing as fuck and everyone's feedback was that it was confusing as fuck, I wonder if they didn't change it.