It probably depends if your artcicle is instructional, informational or interactive.
If it's instructional, then the best way would be to wrap it up with providing contact information for help and feedback.
If it's informational, then then you could provide contact info if there are questions.
If it is interactive; wrap it up with your views, why have taken the position you have on a given topic and then ask; what do you think?
Just allow comments on this one so it will facilitate interaction of readers with one another as well as yourself.
But always - allow commenting.
If your reader wants to say something and you won't let them; they don't have to stay or come back.
Not a pro on this; but try a few options from the feedback that you receive here. Whichever works most like the way you want it to, that's what you should use.