For the LaTeX user trying to use the PSNFSS package, three questions may arise.
First, you have to declare to the DVI driver that you are using PostScript fonts; in the case of dvips, this means adding lines to the psfonts.map file, so that dvips will know where the proper fonts are, and won’t try to find PK files. If the font isn’t built into the printer, you have to acquire it (which may mean that you need to purchase the font files).
Second, your previewer must know what to do with the fonts: see previewing type 1 fonts.
Third, the stretch and shrink between words is a function of the font metric; it is not specified in AFM files, so different converters choose different values. The PostScript metrics that come with PSNFSS used to produce quite tight setting, but they were revised in mid 1995 to produce a compromise between American and European practice. Sophisticated users may not find even the new the values to their taste, and want to override them. Even the casual user may find more hyphenation or overfull boxes than Computer Modern produces; but CM is extremely generous.