Depends on what you need to do. The rich text classes offered in Notes 6 will do a certain amount, but anything beyond that requires DXL/XML manipulation or an API or a third party product. If a third party product is an option at all, you may want to try our
Midas Rich Text LSX, which allows you to create and manipulate many rich text objects "in-place", meaning that you can create a button in a table cell in a regular rich text field, or extract an image and replace it in an image resource, or change the formula on a field on a form or even stored form, etc.