namakaM is housed in kAthaka samhitA under title ” dhruvakshitiH ” , sthAnaka 17 , anuvAka 11-16 , mantra 32-70.
chamakaM is  housed in kAthaka samhitA  under title ” chamAH “, sthAnaka 18 , anuvAka 6-9 , mantra 56-63.

It is commonly recited by families of kashmiri brAhmans.( This is preserved in very well manner by  tradition of kaTha dIkShita-s who were shrauta ritualists as well as well accomplished tantrics )
kaTha rudrIya is generally recited in ekashrutI mode due to distorted learning of kAthaka shAkhA. .Yet some people use to vibrate there voice at evey countering uddAta .Better to quote chArAyanIya sikshA

It is accented in typical style of kAthaka samhitA wher only uddAta svara is marked by vertical bar over the word .
It possess two parts

1) namakaM :-

This portion describes the name or epithets of rUdra, which represent his aspects.
This portion have  mantras describing different aspects of lord rUdra in both peaceful (shAnta ) and terrible ( Ugra ) forms. Additionally, the devotee asks for the benevolent aspect of shiva to be invoked rather than the terrible aspect and requests forgiveness of sins. The original context of the namakaM according to kAthaka srauta sutra  is in shatarUdrIya homa of agnichayan ritual.

2) chamakaM :-

The second part of the text  asks God for fulfillment of wishes. The repeated phrase, cha-me literally means, “and to me [be this granted]”, accompanied by a list of desirables, which are primarily necessary appurtenances for Vedic sacrifices.
The original context of the chamakaM according to kAthaka srauta sutra  is the piling up of the fire-altar of chayan . The hymn invokes, apart from agni and vishnu at the beginning, a pantheon of Vedic deities that are successively linked with Indra to enable the yajamAna or sacrificer/patron to successfully perform Vedic fire sacrifices . It can be interpreted both as a preparatory for a physical external sacrificial ritual, and the inner, possibly yogic sacrifice involving prAnic control, since the yogic “vital airs” are explicitly mentioned as sacrificial adjuncts chamakaM.

vinIyoga

Om asya srI katha rudrIyasya , katha RishI, nAnA chhandAsI,
katha rUdro devatA , srI sAmbasadAshiva prasAda shiddhyartE jape vinIyoga ||

dhyAna

paramashiva rUpa dhyAna :-

nAnA-kalpAbhirAmApaghanam-abhi-matArtha-pradaM suprasannaM |
padaMasthaM pa~nchavaktraM sphaTika-maNi-nibhaM pArvatIshaM namAmI ||

One mediates on sadAshiva rUpa thus:

bibhrad dorbiH kuTAraM mR^igaM abhaya-varau suprasanno maheshaH sarvAla~NkAra-dIptaH sarasija-nilayo vyAghra-charmAttvAsAH |
dhyeyo muktAparAgAmR^ita-rasa-kalitAdri-prabhaH pa~nchavaktras-tryAkShaH koTIrakoTI-ghaTita-tuhina-rochiH kalottu~Nga-mauliH ||
sadyo vedAkShamAlA .abhaya-varadakaraH kunda-mandAra-gauro vAmaH kAshmIra-varNo .abhaya varada parashva .akShamAlA-vilAsI |
akSha-srag-veda-pAshA-.a~Nkusha-Damaruka-khaTvA~Nga-shUlAn kapAlaM bibhrANo bhIMa-daMSTro .a~njana-ruchira-tanur-bhItidashchA .apyaghoraH ||
vidyud-varNA .atha vedA .abhaya-varada kuThArAn dadhat pUruShAkhyaH proktAH sarve trinetrA vidhR^itamukha-chatuShkAsh-chatur-bAhavashcha |
muktA-gauro .abhayeShTAdhika-kara-kamalo .aghorataH pa~nchavaktras-tvIsho dhyeyo .ambujanmodbhava-muraripu-rudreshvarAH syuH shivAntAH ||

One pray to shiva thus by

vishva-grAsAya vilasat-kAla-kUTa-viShAshine |
tat-kala~NkA~Nkita-grIva-nIlakaNThAya te namaH ||

daMShTrA-karAlaM divi nR^ityamAnaM hutAsha-vaktraM jvalanArka-rUpaM |
sahasra-pAdAkShi-shirobhi yuktaM bhavantam-ekaM praNamAmi rudraM ||
namo.astu somAya su-madhyamAya namo.astu devAya hiraNya-bAho |
namo.agni-chandrArka-vilochanAya namo.ambikAyAH pataye mR^iDAya ||

tasmai te deva bhavAya sharvAya pashupataya ugrAya devAya mahate devAya rudrAyeshAnAyAshanaye namaH (svAhA ) ||