code: public boolean importFont(String fontNr, String fontName, String fontFamily, int charset) {
          RtfFont rtfFont = new RtfFont(fontName);
  
          if(charset>= 0)
              rtfFont.setCharset(charset);
          if(fontFamily != null && fontFamily.length() > 0)
              rtfFont.setFamily(fontFamily);
          rtfFont.setRtfDocument(this.rtfDoc);
          this.importFontMapping.put(fontNr, Integer.toString(this.rtfDoc.getDocumentHeader().getFontNumber(rtfFont)));
          return true;
      }
docs: Imports a font. The font name is looked up in the RtfDocumentHeader and
  then the mapping from original font number to actual font number is added.
  
  @param fontNr The original font number.
  @param fontName The font name to look up.
  @param charset The character set to use for the font.