I've got LR 5.7 and I installed (Windows 7/64) the ICC color profile Blurb but I can not use it to create a copy for proofing. How can I do?
See more on this topic in the forum here-
If you are editing and sending a book to blurb within LR, then I don't believe you need a profile.
If you are 'Exporting' images to use for external book editing, then sRGB would be the most appropriate.
Blurb's profile is CMYK and so cannot be used to soft proof in Lightroom. That said, you really do not want to use their profile for anything as they use a lot of different printers and that one profile will not likely represent the printer that is actually used, so it is is useless and might lead you to the wrong path. Expect some variability in color reproduction from them even if you send the same job on two occasions. Nothing you can do to control that unfortunately. Wobertc's advice is spot on. Don't worry about it if you are sending it directly from LR. Use sRGB if you are exporting images to be used in another layout program. Forget about soft proofing for this service.