Can you give us a bit more info? What is your current Sequence Preset, and what is the size/format/CODEC of your Imported footage?
Now, you say that you wish to Crop that footage. Do you mean to actually Crop it (the Crop Effect or similar), or do you mean to Scale it down, so it's still showing the full Frame, but just smaller?
When you Import that Exported footage into a new Project, you do want it to have the exact size of the Exported file, and NOT fill the Frame on the new Project, right?
Are you, by any chance, creating a PiP (Picture in Picture)? If so, there are easier ways to do that, including the Crop.
Good luck, and with that additional info, someone can offer exact details on what you need to choose.
OK here is the additional info, I shot some green screen footage for my Website it is in AVCHD 1080p 1920 x 1080 30 fps I have an actress whom walks out on the screen, I want to be able to shrink her down to about 300 x 350, which I can do on the export, but what my site developer is telling me is that shrinking down the whole video is taking up extrat size and band width, so he wants just the actress potion of the video to be the 300 x 350. so I am not sure how to do this?
Can you make a Custom Project 300 x350 using Desktop Mode
Import your footage and scale to suit.
do your key etc
export as Bill says for FLV