Take care to offset that spike jest a tad to the inside of the open string so it won't be struck by the vibrating open 5th string and "buzz". It also has to be just the right height so it will hold the string down firmly over the fret while retaining enough clearance to slip the string underneath it.

I have mine about 1/8" from the 10th fret and slightly South of the 5th string, head ("hook") pointing towards the 4th string.

The idea came, as I recall, from Pete SEEGER who mentions it in his "How to Play the 5-String Banjo" book published in the '60's.

I like to capo the 5-pinger up about 3 frets to where it sounds like a tenor "Riverboat" banjo to whang away on, make a lot of noise, and have a jolly good time with!