How to programmatically convert an RTF file into a PDF file in VB.NET (ASP.NET) ?

I need to send by SMTP an email in PDF format that I generate from either a PDF template file or RTF template file.
I already send an email in text ok, but need to send PDF.
I tried starting with PDF template file, and then tried to replace its general data fields with specific data (like recipient's name), but PDF is too complex and I can't do find-and-replace.
So I plan to start from RTF template file instead.
My plan is to: 1) Start with RTF template file, replace its general fields (like "Dear ZZZ") with specific data (like "Dear Joe"), and store as RTF specific file. 2) Programmatically in VB.NET convert this RTF file into a PDF formatted file.   (How?) 3) Send by SMTP.