Key change within a chart?

[pdxdjazz]

Is there a preferred way to notate a key change within a chart?

It depends...
Since iRp is (currently) a single-page format, if the form is to be repeated in a different key, it's easy enough to have a page#2 in the 2nd key and just swipe to it.

For classics like MackTheKnife orFever you could indicate the change using text if you want.

Sometimes, within the tune's form the tone-center can change from the default key to a different key for the bridge, (for instance) and then return to the Default key. Usually, this goes unmentioned.

The purpose of charts is to share helpful musical information in a way that can be easily understood by a variety of players.
I hope this helps; is there a specific example you have in mind?
)BOB