As suggested, you can put the file in Source Control and then link to it. However, if you really need to attach the file, you can increase the size limit for the attachments.
Below you will find 2 methods you can use to accomplish this.
Method #1 – Web Service
- Navigate to http://localhost:8080/tfs/<CollectionName>/WorkItemTracking/v1.0/ ConfigurationSettingsService.asmx?op=SetMaxAttachmentSize
- Enter the new value (in bytes, up to 2 GB) in the maxSize field
- Click Invoke
Method #2 – C#
Programmatically, update the value directly in the TFS Registry.