The Apple Computer Inc-Microsoft Corp agreement on type font technology is clearly bad for Adobe Systems Inc, but followers of the Mountain View company’s stock are finding it difficult to assess how bad. The developments banged Adobe’s stock last week, which at one point on Thursday was off $3.50 at $16.25 on four times normal trading volume. Sentiment was not helped by a report in the San Francisco Chronicle that IBM has decided to use the Apple font format in its version of OS/2, the paper quoting IBM as saying that the advanced workstation font arrangement might not be exclusive, although no decision had been made for its other computers.