To apply negative kerning, select the comma, press the Alt key and the
left-arrow key to move the comma over to the left as much as desired.
Note: the amount of a specific shift depends upon the zoom level that
you're viewing the text at in FM.
You can also create a character tag that applies this shift, but you
have to do it via a MIF file and import it into the document to add it
to the catalog. Using a text editor, you can copy and paste the
following and then save as [filename].mif:
<MIFFile 7.00> # Creates a character tag with horizontal shifting
> # end of Font
> # end of FontCatalog
# End of MIFFile
This creates a character tag called "x-minus" that applies a negative
10% shift to the characters. You can adjust the value to your liking
depending upon the font.
Tip: if you change the <FDX ...> to <FDY ...> you can create a custom
vertical shift to apply to characters as well. (You can also combine
these to create custom directional shifts.)