Should I force feed my 8 months old, if he hasn't taken sufficient food?

Personally I would not suggest you to force feed your child. Sometimes force feed g can lead to long time aversion to food and can also make your child picky eater. I think you should give him small meals than full stomach meals. Begin this way and see how things go. Also make him eat at the table with everyone. Treat him like an adult and let him eat himself no matter how messy it would be. Make him sit on his table and chair but along with all family members whenever it is possible else when he is eating make it a playful activity than making it a task.