Step 1: For the Basic of RDLS report follow this link:
Create RDLC report
Step 2: Download the bar code font 3 of 9 from this site:
Barcode Font
Step 3: Then go to your rdlc report page:

Step 4: Right click on the Expression(TextBox) which you want to make barcode->select->"TextBox Properties"

Step 5: Text Box Properties->Font->Select font type->ok
Step 6: Then right click on the Expression(TextBox) which you want to make barcode->select->'Expression'
Step 7: Append '*' to the expression value and click OK.
Step 8: Run your application and you can see your barcode in your report like this.