Is ⻊ just the radical form of 足 (in both traditional and simplified). I keep on mixing them up.

Yep.

I've never seen the 足 form as part of a character.

No doubt there are exceptions somewhere in antiquity...

There are a few words where the 足 form appears on the right hand side as part of a character, however they are very rare.

For example 促进： to promote; advance; accelerate.

The vast majority of the occurrences that I know of are as either as a blank 足 or as the radical form on the left, though.

Note: Skritter's constant telling me that my English spelling is wrong is starting to drive me nuts. Good for my spelling, but still frustrating.

Ah yes, 促 is a common character.

Skritter's telling you your English is wrong :?

Yah.... My English spelling has always been horrible.

Yes, English is my mother tongue. I know...

thanks, thats helpful!

捉 is common as well. Google also turned up 趸 (dun3, buy or sell wholesale) for 足 at the bottom.

http://mandarin.dsturgeon.net/dictionary.pl?if=en&rad=157 has a few more, but mostly seem to be rare enough not to have dictionary definitions.

Here's a good one: 𨆬, three 足s together. No definitions in the online dictionaries.

what about 提? Does it qualify with the additional bar?

Very different... That's got 是 (to be) on the right, which is far flung from 足 (foot) ..!