Hi Rakesh,
I am not quite sure what you are attempting to do. But here is something to think about:
I think what you have is a flow subform and what happens here is all fields within will push up against each other. What you want to do is to enclose your subforms and fields within a position subform.
In the hierarchy tab, you should see:
Page (position content)
flowSubForm (flow content)
< some fields >
positionSubForm (position content)
< some fields >
You should be able to position the 'positionSubForm' to the bottom of the page as long as the bounds of the 'Page' subform extends to the bottom of the page.
John