In Lightroom 6 I can use Soft Proofing to see what my image will look like with different profiles, and I can choose whether to do the conversion using Perceptual or Relative.
However when I actually export the image (i.e as jpeg) I can specify the profile to use and I assume at this point when you click Export it then makes adjustments in the images RGB values to give the best mapping from the LAB values. But you cannot specify whether to use intent perpetual or intent relative - so which one does it use ?
I found some information here https://forums.adobe.com/thread/1083949 for Lightroom 4 but Im finding the thread unclear. But it did open my eyes to the Print to JPEG option in the print tab, is using this just the same as exporting to JPEG but with additional options such as rendering intent or not. For example is it sensible to use this for creating an image to display on a website or can it only be used for creating a jpeg for eventually printing.