How to set font size to rich text box field in crystal report 8.5

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SQL-Server

CrystalReports

I am using vb 6, sql server 2008 and crystal report 8.5. I have a field called Instruction whose data type nvarchar. Previously i was saving plain text data in Instruction field. But now i am saving txtRTF data in Instruction field to save instruction in local language. So now my database contains some records with instructions as plain text and some records of instruction like {\rtf1\ansi\ansicpg1252\deff0\deflang1033{\fonttbl{\f0\fnil\fcharset0 MS Sans Serif;}} \viewkind4\uc1\

When i try to print this data in crystal report. Font size for plain text is different and instruction with rtf data with differnt font size. I want to same size for all records of instruction field. Even I tried to use formula for Font size but it did not work. Please help me. Thank you

What I have tried:

I tried to set font size through edit field option in crystal report. What i did like
After right click on 'instruction' Field in crystal report -> Edit field - > Under font tab, for Size , I have written formula as
If Len(Medical.Instructions}) > 1 then 9 (i.e. set size to 9)