Hi randall su,
The problem is most probably due to the font you have specified for the textbox items. This font should support all foreign characters you would be using in your report. For example you can change the font you use to MS Arial Unicode font, which supports wide varieties of characters. However note that Arial Unicode is around 23 Mb and by default the exported pdf file from the report would embed the whole font, so that it is readable on a machine that does not have it installed. This behavior however is controlled by the FontEmbedding device setting and can be changed to Subset or None. Specifying the Subset option will embed only font glyphs that are used, thus reducing output file size while maintaining portability, while specifying None would not embed that font at all (i.e. the user that is going to read that pdf should have Arial Unicode installed on his machine. You can learn more about altering these values from the Configuring Telerik Reporting Config Section help article.
the Telerik team