Can I add a cover letter to my proposal?

There isn't a "cover letter" section, but you can create a section that has no header, which works very well for a cover letter.

To create a section that you can use as a cover letter, go to your sections menu and click on the "new section" button to create a new section.

When you're creating a title for your section,  make sure to use curly braces around the title. By doing this, the title will not appear on the client's version of the proposal. You'll be able to see it in your Bidsketch (making it searchable), but it will appear without a headline on the proposal itself. Type in your cover letter, and save your section. (Note the use of variables here to ensure the accuracy of information.)

When you're ready to send the proposal, it will look like this: