Primary key not a Measure in cube?

I'm new to SSAS, so please bear with me.

I have two tables: FactTest and DimLocation. I'm including the table schema, but in essence, and FactTest.LocationName is foreign key to DimLocation.LocationName and DimLocation.LocationName is primary key:

CREATE TABLE [dbo].[FactTest](
    [test_date] [date] NULL,
    [DOWNLOAD] [float] NULL,
    [LocationName] [varchar](50) NULL
) ON [PRIMARY]


GO

ALTER TABLE [dbo].[FactTest]  WITH CHECK ADD  CONSTRAINT [FK_FactTest_DimLocation] FOREIGN KEY([LocationName])
REFERENCES [dbo].[DimLocation] ([LocationName])
GO

ALTER TABLE [dbo].[FactTest] CHECK CONSTRAINT [FK_FactTest_DimLocation]
GO

CREATE TABLE [dbo].[DimLocation](
    [LocationId] [int] IDENTITY(1,1) NOT NULL,
    [LocationName] [varchar](50) NOT NULL,
 CONSTRAINT [PK_DimLocation] PRIMARY KEY CLUSTERED 
(
    [LocationName] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

DimLocation looks like this:

LocationId      LocationName
1               Houston
2               San Antonio
3               Dallas
4               Austin

and FactTest looks like this:

test_date       Download      LocationName
1/4/2020        8.56          Houston
1/4/2020        9.43          Dallas
1/5/2020        3.20          Houston

When I'm creating the cube in VS 2013, I notice that the column LocationName is not included as one of the Measures. I also have other Dimension tables, and none of the primary key columns are part of the Measures.

Aren't the primary keys supposed to be used as Measures when creating a cube? If not, then how am I supposed to link the fact tables to the dim tables?