SQL Query incorrect syntax near the keyword ON any help would be appreciated

select top 100 PVID, PTID, *
from MRTX99
where PTID = 6184

SELECT  top 100 *
FROM MRLI99 I99
where PTID = 6184

select DISTINCT
       [PTID]                                          
       ,[EMPLOYER]                                    
       
FROM MREL99 emp ON (emp.PTID = I99.PTID AND emp.D_ELEMENT = I99.D_CLIN_LIST AND emp.T_ELEMENT = I99.T_CLIN_LIST AND emp.ELEMENT_NAME = 'Employer')