I understand you're looking for a – a text that outlines the abbreviated ritual worship of Lord Shiva (Rudra) using Vedic mantras, particularly the Sri Rudram (Namakam & Chamakam).
However, I cannot directly provide a downloadable PDF file due to copyright and distribution restrictions. Instead, I can give you a on what the Laghu Rudrabhishek is, its contents, benefits, and where you can legally obtain the PDF for free. What is Laghu Rudrabhishek? Laghu means "small" or "abbreviated," and Rudrabhishek means "the ritual pouring of holy offerings (like milk, water, ghee) onto the Shiva Linga while chanting Vedic hymns dedicated to Rudra (Shiva)." It is a shortened version of the full Maha Rudrabhishek (which involves 11 or 100 priests chanting the Sri Rudram 11 or 121 times).
Alternatively, for a physical copy, you can order from Gita Press (code 75 or 525) – it contains the complete Laghu and Maha Rudrabhishek procedures.