There are a few things going on here, it isn't a one factor problem, so lets take it apart.
Hi everyone,
I shot some Pan-F+ in the studio yesterday, and I chose to expose it at ISO 25 instead of 50, as I read that would work better in contrasty lighting.
First, contrast and subject placement are at the most basic level is a product of the lighting in the scene.
In this case, in a studio, the lighting is controlled so the contrast and subject placement have technically been fully controlled.
I've heard that Pan-F can blow the highlights quite easily and that is something I'd want to be very careful about considering the lighting I used (blown out foreheads don't look too nice). Any ideas?
Negative films don't blow their highlights easily. Slides sure, but not negatives. IMO the thought that Pan-F or any negative film "blows it's highlights easily" is an urban myth based in people thinking negative shooting & printing works like it does with slides in that there is "one perfect exposure and one perfect development that will yield a perfect print."
Instead negative films almost universally have a significant amount of overexposure latitude. Pan F is not an exception to this rule. What I'm saying is that negatives normally catch a lot more highlight detail than we ask them to print. Your choice to use EI 25 instead of 50 simply means that you have extra shadow detail on the negative (that you may or may not use) not that highlights get blown out on the negative. You can still print the same highlights you just need to make a print exposure adjustment.
The problem isn't the negative.
When people talk about blown highlights and they are printing from negatives, IMO they are really saying, "the highlights don't straight print easily."
The fix for that can be softer development of the film (pulling or minus development), a softer paper grade, burn and dodge, or in your case here the use of controlled lighting in the studio.
IMO for shots on any film that are done in studio lighting there should be no reason to deviate from "normal" film development. The contrast and highlights should already be right if the studio was set up well. Adjustments will be small and easily corrected with VC printing methods.
However I'm not quite sure how I should develop the film now. I think I want to develop in Rodinal to achieve high acutance, but at what dilutions and times I don't know.
Next, The acutance decision is a separate decision from contrast. Just using Rodinal in place of a more solvent developer is a big step that direction. If the above logic makes sense to you then just pick a scheme that gets you normal contrast on the negative.