The following are some scriptural quotes to show that the practices of gopIchandanadhAraNa and the taptamudrA~Nkana concepts are scripturally sanctioned. They have been taken from 'chakramImamsa' written by Sri vijayIndratIrtha. The author devotes some part of the book to vindicate the acceptance of pancharAtrAs as prAmANa.

In scriptures

taittarIya
charaNa.m pavitra.m vitata.m purANa.m yena pUtastarati duShkR^itAni |
tena pavitreNa shuddena pUtA atipApmAnamarAtintarema ||

lokasya dvAramarchiShmatpavitra.m jyotiShmad bhrAjamAna.m mahasvat |
amR^itasya dhArA bahudhA dohamAna.m charaNa.m no loke sudhitAndadhAtu ||

R^igveda 9.96.19
chamUShacChayenaH shakuno bibhR^itvA govindurdrapsa AyudhAni bibhrat |
apAmUrmi.m sachamAnaH samudra.m turIya.m dhAma mahiSho vivakti ||

(A Verified quote: A detailed explanation is available in the book).

bR^ihadAraNyaka
nichikshepa suShaNa.m bhidyamAna.m madhye bahumadadhatsudarshanam |
viShNorida.m bhUrida.m bhUritejaH pradharShati divAnakta.m bibhR^iyustajjanAsaH ||

bhAShkala shAkhAyAm
prate viShNo abjachakre pavitre janmAmbhodhi.m tartave charShaNIndrAH |
mUle bAhvoH dadhate purANA li~NgAnya~Nge tAvakAnyarpayanti ||

AtharvaNa mahopaniShadi
dakshiNe tu bhuje vipro bibhR^iyAdvai sudarshanam |
savye tu sha~Nkha.m bibhR^iyAditi brahmavido viduH ||

kaThashAkhAyA.m
dhR^itordhvapuNDraH shR^itachakradhArI viShNu.m para.m dhyAyati yo mahAtmA |
svareNa mantreNa sadA hR^idi sthita.m parAtpara.m yanmahato mahAnta.m ||

R^igveda khilA
chakra.m bibharti vapuShA.abhitapta.m bala.m devAnAmamR^itasya viShNoH |
sa eti nAka.m durita.m vidhUya prayAnti yadyatayo vItarAgAH ||

AtharvaNe
ebhirvayamurukramasya chihnaira~NkitA loke subhagA bhavema |
tadviShNoH parama.m pada.m ye.anugacChanti lA~nChitAH ||

maitrAyaNIya shAkhAyA.m
pavitramityagniH agnirvai sahastrAraH sahastrAreNa neminA taptatanuH brahmaNaH sAyujya.m salokatAmApnoti - iti

In smR^itis, itihAsa and AgamAs

(vR^Iddha)manu smR^iti
UrdhvapuNDra.m tathA chakra.m nitya.m dhArayate hi yaH |
tena tasyAshubha.m nashyet shubhamasya vivardhate ||

shANDilya
pashuputrAdika.m sarva.m gR^ihopakaraNani cha |
a~NkayecCha~NkhachakrAbhyA.m nAma kuryAccha vaiShNavam ||

sha~Nkha
upavItAdivaddhArya.m sha~NkhachakragadAdika.m |
brAhmaNasya visheSheNa vaiShNavasya visheShataH ||

yama
upavItI shikhI vipraH chakralA~nChanasa.myutaH |
chakralA~nChanahInasya viprasya viphala kriya

vyAsa
lalATe tu gadA dhAryA mUrdhni chApasharau tathA |
hR^inmadhye nandakaschaiva sha~Nkachakre bhujadvaye ||

mahAbhArata - bhIShma parva
brAhmaNaih kshatriyairvaishyaiH shUdraischa kR^italakshaNaiH |
archanIyascha sevyascha nityayuktaiH svakarmasu ||

hariva.msha
chakrA~NkitAH praveShTavyAH yAvadAgamana.m mama
nAmudritAH  praveShTavyAH  yAvadAgamana.m mama

viShNu dharme, yama ki.mkara sa.mvAde
bhavatA.m bhramatAmatra viShNusa.mshrayamudrayA |
vinAj~nAbha~NgakR^innaiva bhaviShyati naraH kvachit ||

puNDarIkhyAne
kechicChakrA~NkitAstatra prANinaH puNyadarshinaH |
vicharanti yathAkAma.m puNyatIrthaprasha.mshinaH ||

In the Puranas

garuDa
agninaiva tu sa.myukta.m chakramAdAya vai dvijaH |
dAhatyetsarvavarNAnA.m harisAlokyasiddhaye ||

vArAhe
achakradhAriNa.m vipra.m yaj~nArthe bhojayiShyati |
retomUtrapurIShAdi svapitR^ibhyaH prayacChati ||

brahmAnDe
sha~NkhachakrA~NkitAn bhaktyA yaH pUjayati mAnavaH |
sa sAkshAdviShNusAmIpya.m labhate nAtra sa.mshayaH

brahmavaivarte
chakrA~Nkitabhuja.m martya.m yo vai nindati mUDhadhIH |
prayAti naraka.m ghora.m yAvadAbhUtasamplavamiti

bhaviShya
chakrA~Nkitabhuja.m ddaShTvA yastu ta.m nAbhivAdayet |
tiryagyonishata.m prApya viShThAyA.m jAyate krimiH ||

mArkaNDeya
chakrAdidhAraNa.m pu.msA.m harisa.mba.mdhavedina.m |
pativratAnimitta.m hi valayAdi vibhUShaNa.m ||

vAmana
lIlayApi likhedyastu bAhumUle sudarshaNam |
kulakoTi.m samuddhR^itya sa gacChedvaiShNava.m pada.m ||

brahma
sharIra.m ddashyate yasya kR^iShNachakreNa lA~NChita.m |
ga~NgAjalamaya.m manye deha.m tatpApavarjita.m ||

matsya
viShNuchakrA~Nkita.m deha.m pavitramiti vai shrutiH |
dhArayedviShNubhaktastu chakra.m bAhau tu dakshiNe ||
vAme tu sha~Nkha.m rAjanta.m vaiShNava.m padamApnuyAt iti|

pAdma
gopIcha.ndanato nitya.m lA~nchito yasya vigrahaH |
sha~NkhachakragadApadmaiH dehe tasya sadA hariH ||

...more to come.