Here's an idea...

USE tempdb;
GO

IF OBJECT_ID('tempdb.dbo.Skill', 'U') IS NULL
BEGIN -- DROP TABLE tempdb.dbo.Skill;
    CREATE TABLE tempdb.dbo.Skill (
        skill_id INT NOT NULL IDENTITY(1,1),
        skill_name VARCHAR(30) NOT NULL
        CONSTRAINT pk_Skill PRIMARY KEY CLUSTERED (skill_id),
        CONSTRAINT uq_Skill_skillname UNIQUE (skill_name)
        );

    INSERT tempdb.dbo.Skill (skill_name) VALUES ('C#'), ('.net'), ('C++'), ('T-SQL'), ('PL SQL');
END;

IF OBJECT_ID('tempdb.dbo.Candidate', 'U') IS NULL
BEGIN -- DROP TABLE tempdb.dbo.Candidate;
    CREATE TABLE tempdb.dbo.Candidate (
        candidate_id INT NOT NULL IDENTITY(1,1),
        first_name VARCHAR(30) NOT NULL,
        last_name VARCHAR(30) NOT NULL,
        CONSTRAINT pk_Candidate PRIMARY KEY CLUSTERED (candidate_id)
        );

    INSERT tempdb.dbo.Candidate (first_name, last_name) VALUES
        ('Bob', 'Jones'), ('Mary', 'Baxter'), ('Kevin', 'Hall'), ('John', 'Doe'),
        ('Alison', 'Chains'), ('Molly', 'Hatchet'), ('Maxwell', 'House'), ('Red', 'Fox');
END;

IF OBJECT_ID('tempdb.dbo.CandidateSkills', 'U') IS NULL
BEGIN -- DROP TABLE tempdb.dbo.CandidateSkills;
    CREATE TABLE tempdb.dbo.CandidateSkills (
        candidate_id INT NOT NULL,
        skill_id INT NOT NULL,
        proficiency_level INT NOT NULL
            CONSTRAINT ck_CandidateSkills_proficiencylevel CHECK (proficiency_level BETWEEN 1 AND 5),
        CONSTRAINT pk_CandidateSkills PRIMARY KEY CLUSTERED (candidate_id, skill_id)
    );

    INSERT tempdb.dbo.CandidateSkills (candidate_id, skill_id, proficiency_level) VALUES
        (1, 1, 3), (1, 2, 2), (1, 5, 4), (2, 1, 4), (2, 3, 2), (2, 4, 1),
        (3, 4, 5), (3, 1, 1), (4, 5, 5), (5, 1, 2), (5, 2, 2), (5, 3, 3),
        (5, 4, 1), (5, 5, 2), (6, 2, 4), (6, 4, 4), (7, 1, 3), (7, 3, 3),
        (6, 5, 2), (7, 5, 5), (8, 1, 4), (8, 4, 4);
END;

--SELECT * FROM dbo.Candidate c;
--SELECT * FROM dbo.Skill s;
--SELECT * FROM dbo.CandidateSkills cs;

--=======================================================================================

DECLARE
    @skill1 INT = 1,
    @skill2 INT = 2;

WITH
    cte_required_skills AS (
        SELECT
            s.skill_id
        FROM
            ( VALUES (@skill1), (@skill2) ) s (skill_id)
        ),
    cte_cs_eval AS (
        SELECT
            cs.candidate_id,
            cs.skill_id,
            cs.proficiency_level,
            skill_count = COUNT(1) OVER (PARTITION BY cs.candidate_id),
            total_proficiency = SUM(cs.proficiency_level) OVER (PARTITION BY cs.candidate_id)
        FROM
            cte_required_skills rs
            JOIN dbo.CandidateSkills cs
                ON rs.skill_id = cs.skill_id
        )
SELECT
    c.candidate_id,
    c.first_name,
    c.last_name,
    s.skill_name,
    ce.proficiency_level
FROM
    cte_cs_eval ce
    JOIN dbo.Candidate c
        ON ce.candidate_id = c.candidate_id
    JOIN dbo.Skill s
        ON ce.skill_id = s.skill_id
WHERE
    ce.skill_count = 2  --<< number of required skills.
ORDER BY
    ce.total_proficiency DESC;