All I wanted is a simple link the user can click on to change to an alternate form. We don't want to change the default form, but for a subset of users, in about 1% of cases, they need to access some additional information that we don't want to show by default, and don't want to print out on the standard PDF. The alternate form has extra information and a different PDF template. I don't know if this is the best way to do it, but it required no scripting or maintenance, so it seemed like a reasonable approach for the amount that it will be used.

I think this will do what you want. try 1. use an on record load worklflow to add button to the form. 2. The button transitions to state 2. 3. on entry to state 2, the workflow action is a set field value, setting the customform field to the new form?

Thanks, that's a good suggestion, though since the inline HTML works, I think we'll stick with it. We get so few of these requests we didn't really want to even have the overhead of a workflow. It would be running all the time, and yet almost never utilized. These are super-rare requests, just a few times per year.