From Hugh Hewitt's quote of Robert Cartwright, computer scientist and typography expert at Rice University:

The typed text in the "Killian memos" is kerned (check out letter combinations like "fo" and "fe"), but the Composer text is clearly not. Kerning is a computationally complex task beyond the capacity of any mechanical typewriter--even one as expensive and elaborate as the IBM Selectric Composer. Moreover, the proportional spacing in the sample text is rather crude (look at the typesetting of "11" for example) which is the best that a mechanical typewriter--even one as complex as the Composer--can do.

CBS pdf of the May 19 memo.

Zoom in on the "fo":

Is this the smoking kern? More on kerning:

Judge for yourself.

(btw, this is GC. I removed myself from the MT control panel because I wanted to take some time off from blogging, so I had to post under a co-blogger's account. However, this scandal broke just then and I thought this was worth posting.)

Update:

Like CBS, the original document was tilted to the left. I did my best to correct for it and added some horizontal guides:

It does seem as if the f is excluding volume above the o, even taking the rotation of the original document into account.