Both Termidor SC (fipronil for termites) and Bora-Care will work, but Bora-Care is typically the better one to use for this situation. Termidor is not a wood treatment product, so for it to work you have to drill holes EXACTLY where the termites are and it has to touch the termites to work. If you miss where they are, it will not work. Also, Termidor does not really have any residual in the wood, so after you treat inside the wood with Termidor and it dries, that wood is exposed for future termite and beetle infestations.
Termidor: http://www.domyownpestcontrol.com/termidor-sc-p-184.html
Bora-Care is usually the preferred choice if most of the wood is exposed and it is raw wood you are treating, meaning it is not painted, stained, or sealed, it is just normal wood. Bora-Care is made only for wood, and you do not have to know exactly where the termites are for it to work which is a plus. Bora-Care is sprayed evenly over all exposed surfaces of the wood and actually penetrates through the entire piece of wood. When the termites in the wood try to consume the wood after it has been treated, they ingest the Bora-Care with the wood and die. No matter where they are in the wood the Bora-Care will find them as long as you treated the exposed wood that you can see. The other main benefit is that Bora-Care stays in the wood forever, so you will not have to worry about termites or beetles infesting the wood that you treated ever again.
Bora-Care: http://www.domyownpestcontrol.com/boracare-p-100.html
Yes, Boracare can (and in many instances MUST) be used on pressure treated wood. As a termite barrier under Section VI of the label it is required to be applied twice to exterior wall sill plate and that is always pressure treated.
All pressure treated wood that is cut or drilled MUST have a field treatment or end cut application in order to meet building code (including sill plate in a home - see IRC 2016 and AWPA Standard M4).
It is also useful to treat pressure treated wood as the heartwood is not treated properly by pressure treatment (especially refractory species such as Douglas fir, and the transition wood of pine decking is often the first to rot out and will greatly benefit from a treatment with Boracare with Moldcare at 5 years (see Lloyd et al., 2013).
Posts, piles and poles also have the heartwood issue and can be treated but this is often best done with Jecta.