Sounds like you have a nonstandard form, but that shouldn't be a problem. On a standard form, Box 1 has the dollar amount of the gross distribution and Box 3 has the distribution code, which is usually a "1". When you are on the 1099-SA entry screen in TurboTax, enter the $603.46 in Box 1 - Gross distribution and select "1-Normal distribution" from the drop-down menu under Box 3 - Distribution code. (Click the screenshots below to enlarge them for reference.)