High SOS_SCHEDULER_YIELD and Signal Waits I have run Paul Randals wait script and can see SOS_SCHEDULER_YIELD is at 60% with an average signal wait of 10ms.  I have also run a script to find out the what percentage of my waits are signal waits and in total it is 47%.

I can seen in task manager that the CPU usage is high and I believe I do have a CPU issue, but how do I find which queries are the ones causing the signal waits?

Just to update:  The version of SQL is 2008R2
Recent expensive queries in the Activity Monitor in SSMS should be your first stop. 

For more information grab SP_Whoisactive and find Glenn Berry's diagnostic queries which will help you a lot. The exact query depends on the version of SQLServer but this should be a start.

SELECT TOP(50)
  creation_time
 ,last_execution_time
 ,(total_worker_time+0.0)/1000 AS total_worker_time
 ,(total_worker_time+0.0)/(execution_count*1000) AS [AvgCPUTime]
 ,execution_count
 ,st.text
FROM sys.dm_exec_query_stats  qs
CROSS APPLY sys.dm_exec_sql_text(sql_handle) st
 WHERE total_worker_time &gt; 0
ORDER BY total_worker_time DESC