code: public void setRGBColorFillF(float red, float green, float blue) {
          HelperRGB(red, green, blue);
          content.append(" rg").append_i(separator);
      }
docs: Changes the current color for filling paths (device dependent colors!).
  <P>
  Sets the color space to <B>DeviceRGB</B> (or the <B>DefaultRGB</B> color space),
  and sets the color to use for filling paths.</P>
  <P>
  Following the PDF manual, each operand must be a number between 0 (minimum intensity) and
  1 (maximum intensity).</P>
  
  @param   red     the intensity of red. A value between 0 and 1
  @param   green   the intensity of green. A value between 0 and 1
  @param   blue    the intensity of blue. A value between 0 and 1