I have no experience with MICR font but I do have some with bar codes, and you have to do two things, 1-use a formula to convert the data to the code and 2-format the formula field as a barcode. I would guess your situation would be similar.
The funtion I used in my formula is not normally a part of CR and is a UFL that came with the software, as want the font.
I hope this helps. Software Support for Macola, Crystal Reports and Goldmine
dgilsdorf@mchsi.com