Q:

Maintaining the size and position of the Control in the form

I want to maintain size and position of the control relative to its container eg,size and position of the richtextbox in the form should be maintained when form resize.

A:

If I understand you correctly, you need to use the Anchor property.
Have a look at Control.Anchor Property.

A:

If you have more complex designs, just a anchor and docking is not enough. Imagine you have two textboxes and while resizing you like that both boxes grow and shrink (by 50% for each one). In that case you can use the TableLayoutPanel with relative sizes and within these panels you arrange your controls with anchoring and docking.
Another helpful thing: In a more complex design you should take a look into View - Other windows - Document Outline, while you're in Design View and you get a great overview about where which control resides.

