I found it on my forms. I selected the 1040 from the forms list. Scroll down to line 12b, then move to the right to the space just to the right of where you see 12b in the middle of the page, then click on that space. It will take you to the 1040 worksheet and should bring you right to the point on that screen to input 300. It is 12b again and should be highlighted in yellow. Once you put the 300 in this space, it carries it through to the main 1040 page and should recalculate your tax or refund amount. It did for me, and I have not yet filled in all the pages yet. I did this to see if it would work, and it seems to at this point.
