Can't create Foreign Key in Sql Server

Question

I have two tables: SDCUST and the newly created SDRTS (defined below).

SDCUST table definition

DROP TABLE SDRTS
  GO
  CREATE TABLE SDRTS(
    BGTID int NOT NULL,
    RTSID uniqueidentifier NOT NULL,
    CONSTRAINT PK_SDRTS PRIMARY KEY CLUSTERED (BGTID,RTSID),
    CUSTID uniqueidentifier NOT NULL,
    CONSTRAINT FK_SDRTS_SDCUST FOREIGN KEY(CUSTID)
    REFERENCES SDRTS(CUSTID),
    BGRPID_1 uniqueidentifier NOT NULL,
    BGRPID_2 uniqueidentifier NOT NULL,
    INCRT FLOAT NULL,
    CURRID int NOT NULL,
    EDATE datetime NULL,
    EUSRID uniqueidentifier NULL,
    UDATE datetime NULL,
    UUSRID uniqueidentifier NULL,
    V001 float NULL,

I want CUSTID to be the foreign key on the new table, but I get an error:

Msg 3701, Level 11, State 5, Line 1 Cannot drop the table 'SDRTS', because it does not exist or you do not have permission.
Msg 1776, Level 16, State 0, Line 3 There are no primary or candidate keys in the referenced table 'SDRTS' that match the referencing column list in the foreign key 'FK_SDRTS_SDCUST'.
Msg 1750, Level 16, State 0, Line 3 Could not create constraint or index. See previous errors.

How can I create this key?

Answer 1

Just to follow up on the comments this was resolved by:

Add both columns. CONSTRAINT FK_SDRTS_SDCUST FOREIGN KEY(BGTID, CUSTID) REFERENCES SDCUST(BGTID, CUSTID)