The striker bagged a late goal for his side on Wednesday. It was his first appearnce since returning to training. His strike wasn't enough, the Gils crashed out of the Worthington Cup, losing 2-1 to Chelsea.
Player-boss Hessenthaler is hoping his side can record another three points on Saturday in order to draw level on points with the high-flying Royals.
The rookie boss may well play 21-year-old King up-front as he is sure to get a rapturous reception from the Preistfield Stadium crowd.
Hessenthaler told readingfc.co.uk: "You could see by the reception Marlon got from our fans at Chelsea that they were pleased for him. I was pleased to see him get out there and hopefully his goal will be the first of many."
Gillingham put in a creditable performance at Chelsea and only lost by one goal which pleased Hessenthaler.
He added: "I thought we played quite well at Chelsea because they were a difficult side to break down. We had a lot of the ball, but then they let you have the football and hit you on the counter-attack.
"It was nice to get a goal at the end for all our efforts that we put in. All-in-all I think it's a good confidence booster for Saturday."
The Gils are confident going into Saturday's game, Hessenthaler commented: "We really need to get three points on Saturday. Hopefully the Chelsea performance will help towards that game and we'll get the points."