Creating PDF files from AutoCAD that allow text searching throughout the entire document and at the highest level of compression, requires the use of True Type Fonts (TTF) in your AutoCAD drawings.
There are some conditions that must be met to ensure proper conversion of True Type Fonts in AutoCAD to PDF. These are AutoCAD limitations in how it determines in the output stream to treat text.
The width factor must be 1.0. Modifying the width value in AutoCAD will prevent the TTF from converting as text to PDF.
The oblique angle within the style must be set to 0.0. Modifying the oblique angle in AutoCAD will prevent the TTF from converting as text to PDF.
The font must not be set to "Fit"
The font must have a Z coordinate of 0.0
If the font is part of a block the X and Y scale factors must be the same.
In additon the Adobe PDF Specification specifies a set of 14 fonts that must be available to every PDF reader: Helvetica (normal, bold, italic, bold italic), Times (normal, bold, italic, bold italic), Courier (normal, bold, italic, bold italic), Symbol and ZapfDingbats. So if you use only these fonts in your AutoCAD drawings you do not have to embed the fonts because even if the user does not have the font installed the software that they are using to view the PDF file is supposed to have them. This is also true for Apple, Unix, and Linux systems.
Many firms have AutoCAD drawings that contain more than one font. Some fonts are TTF and others are either SHX or custom fonts. The SHX fonts don't convert as text on PDF files. They convert as outlines and curves which increase the PDF file size dramatically. For a firm to simply stop using a custom font so that the PDF's its designers create are text searchable and smaller in size is like asking an artist to paint with only one brush.
There is a solution. Firms that have custom fonts or SHX fonts that they use on a daily basis as a part of their drawing standards can have these fonts converted into a TTF that will install as a Windows font. By converting their in-house fonts to TTF they will be able to maintain their current drawing standards and enjoy the benefit of creating PDF's that are text searchable and significantly smaller in file size.
TC Fonts (www.tcfonts.com) is a company that will convert your SHX and custom fonts to true type fonts. You must be specific in letting them know that the SHX font needs to be converted to true type font, because they also have software that will convert true type fonts to many CAD font formats.