My son is 17 months old and luckily we haven't had any problems with eating yet. So here's what has worked for us:
1) Sit down and eat with him when you get the chance. I know you're working, so that makes it hard, but eating dinner together is important.
2) Make sure he's eating what you're eating. At this age, they're starting to like to be "big" like you, even if they can't say so.
3) Let him sit at the table with a booster rather than a highchair. Put his food on a plate and let him practice with a fork and spoon. My little guy LOVES this, and gets a few extra bites to his mouth using the fork.
4) Offer 2-3 options on his plate, one of which you know he'll eat. If he finishes that, he either eats the rest, or is done.
5) Let him graze throughout the day. They've got so much going on that sometimes they don't want to sit still long enough to fill their tummies. They also have small tummies that can't hold as much, and even nutritionists say that more small meals a day is healthier than three large ones.
6) RELAX! It's not important how much he eats in a single sitting, it's important what they eat over the course of time. If he's gaining weight, meeting his milestones, and is happy and healthy, then don't worry about each individual meal. Not to mention one serving of food for them is 1/4 the size of an adults. So eating a few bites is ok! My son is a pretty good eater, who likes a variety of foods, and is still breastfeeding, but is a lean 21-22 lbs at 17 months. So don't worry, and don't turn mealtimes into battles by trying to force it. good luck!