SDK - Send Email Using Template with attachement

 InstantiateTemplateRequest instTemplateReq = new InstantiateTemplateRequest  
           {  
             TemplateId = templateId,  //template guid
             ObjectId = incidentId,   // template type id
             ObjectType = "incident"  
           };  
 InstantiateTemplateResponse instTemplateResp = (InstantiateTemplateResponse)service.Execute(instTemplateReq);  
 Entity instTemplate = (Entity)instTemplateResp.EntityCollection.Entities[0];  
 Guid emailGuid = service.Create(instTemplate);  
 //Add attachement  
 Entity emailAttachment = new Entity("activitymimeattachment");  
 //attachement in byte[]  
 emailAttachment["body"] = Convert.ToBase64String(attachement);  
 emailAttachment["objectid"] = new EntityReference("email", emailGuid);  
 emailAttachment["objecttypecode"] = "email";  
 emailAttachment["filename"] = item.Name;  
 service.Create(emailAttachment);  //Creates attachement to email
 SendEmailRequest sendEmailReq = new SendEmailRequest()  
           {  
             EmailId = emailGuid,  
             IssueSend = true  
           };  
  SendEmailResponse sendEmailResp = (SendEmailResponse)service.Execute(sendEmailReq);