Fontbook doesn’t recognize PostScript fonts directly. It sees them only via a suitcase (screenfont) file.
To install them, double-click on the suitecase file or drag it onto the FontBook icon.
OSX will generally not let you see the screen fonts stored in the suitcase file but uses the linked PostScript fonts for screen display instead. However, all the style, metrics and kerning information is stored in the suitcase file. PostScript font files by themselves cannot be installed and nothing will happen if you try to open them in FontBook.
Font suitcases no longer have an icon that looks like a suitcase. Instead, look for the letters FFIL on the icon. “Font Suitcase” will also be shown as “Kind” in the Finder.