Install PFX certificate on SQL 2008 R2
Plase try to follow this steps:

Launch the Microsoft Management Console. Select File &gt; Add/Remove snap-in:



Add a Certificates snap-in:



Select “Computer account”:



Use the Local Computer:



With the snap-in now configured, right-click on the “Personal” certificate store folder, select All Tasks &gt; Import:



Use the certificate import wizard to select the .PFX file to import.
In either case, follow the import wizard instructions. Enter the password set when the PFX file was created. Ensure that “Include all extended properties” is selected:



Select “Place all certificates in the following store” and choose the “Personal” store:


Once the certificate has been imported, SQL Server must be configured to use it. The SQL Server configuration manager for SQL Server 2008/R2 has an option to set the certificate associated with an instance, by opening the “SQL Server Networking Configuration,” right-clicking on “Protocols for ,” and opening the Certificate tab. However, this method cannot be used to select any certificate other than a machine certificate for servers that belong to a domain.

Find the “Thumbprint” of the certificate, and copy it to the clipboard. In the certificate management console, it can be found by opening the certificate, selecting the “Details” tab, scrolling to the bottom of the field list, and selecting “Thumbprint”:



After locating the thumbprint, copy it out of the certificate viewer, paste it into notepad, remove all of the spaces, and copy the modified thumbprint back to the clipboard. Be careful – it’s easy to make a mistake.

Open regedit
Navigate to: HKLM\Software\Microsoft\Microsoft SQL Server\MSSQLServer\SuperSocketNetLib
Locate the “Certificate” entry
Assign its value to the thumbprint copied out of the certificate, e.g.:




The instance must be restarted for the changes to take effect.